This section is from the book "Plumbing Estimates And Contracts", by J. J. Cosgrove. Also available from Amazon: Plumbing estimates and contracts.
Trade discounts are reductions made by manufacturers or jobbers to those regularly engaged in the plumbing business from the prices listed in their catalogues. Discounts are computed by the rules of percentage, the list price of goods being the base, and the discount the rate. "When several discounts in series are allowed on certain goods - as, for instance, when a discount of 40, 10 and 5 is quoted on soil pipe - the first discount, that is, 40 per cent., is deducted from the list price; the second discount, that is, 10 per cent., is then deducted from the remainder, and the remainder so obtained is again lessened by subtracting from it 5 per cent. For instance, if a discount of 40, 10 and 5 be allowed on a bill of soil pipe, the list price of which amounts to $100, 40 per cent, would be deducted from this
April 10, 1910
Page | Discription of Materials........................ | Discount Per Cent |
1 | Cast Iron Soil Pipe........................................ | 20-10 |
2- 8 | Cast Iron Soil Pipe Fittings................... | 20-10-5 |
9 | Wrought Pipe................................................ | 30 |
10- 21 | Recessed Drainage Fittings.......................... | 30-7-2 1/2 |
22- 30 | Malleable Fittings.......................... | 30-10-10 |
31- 38 | Cast Iron Steam and Water Fittings........ | 40 |
39- 68 | Pipe Fitters' Tools............................ | Prices net |
69- 76 | Brass Globe 'and Angle Valves, 2" and smaller..................................................... | 15-5 |
Brass Globe and Angle Valves, larger than 2"......................................................... | 10-10-5 | |
77- 84 | Railing Fittings...................................... | 25 |
85- 93 | Brass and Copper Pipe and Fittings.......... | 20-2 1/2 |
94 | Galvanized Range Boilers............................ | 15-10-10 |
95- 96 | Copper Range Boilers.................................. | 10 |
97-100 | Compression Brass Goods...................... | 20 |
101-106 | Fuller Brass Goods........................................ | 20-5 |
107 | Brass Ferrules and Cleanouts...................... | 30 |
108-112 | Lead Traps and Bends.................................. | 30-5-7 1/2 |
113-145 | Porcelain Enameled Baths.......................... | 12 1/2 |
146-152 | Porcelain Baths.............................................. | 15 |
153-176 | Closet Combinations...................................... | 10 |
177-200 | Lavatories....................................... | 10-5-5 |
201-210 | Porcelain Enameled Wash Trays................ | 15 |
211-222 | Porcelain Wash Trays.................................. | 17 1/2 |
223-230 | Slate and Soapstone Laundry Trays.......... | 20 |
231-253 | Porcelain Enameled Sinks............................ | 30 |
254-262 | Porcelain Sinks...................................... | 33 1/3 |
263 | Plain and Galvanized Black Iron Sinks.... | 20 |
NOTE - This discount sheet supersedes all previous issues.
All lists, discounts and questions are subject to change without notice. We will endeavor, however, from time to time, to advise our customers of variations in prices.
TERMS - Net cash 30 days, 2 per cent. discount 10 days.
Boxing, crating and packages will be charged at manufacturers' rates.
Fig. 35.
amount, leaving a balance of $60. From this balance 10 per cent., or $6, would be deducted, leaving a balance of $54, and 5 per cent. taken from $54 would leave a net price for the goods of $51.30. Instead, however, of deducting the three separate discounts the equivalent of the three can be ascertained and the equivalent discount deducted from the base. For instance, the equivalent of 40, 10 and 5 is .4870 and 100 x .4870 = $48.70, which subtracted from $100 leaves $51.30.
Instead of finding the discount on a purchase, then subtracting the discount from the list price, a quicker and easier way is to find the percentage remaining after the discount has been deducted and multiply the list price by the remaining percentage. The remaining percentage is always found by subtracting the rate or discount from 100.
For example, if the cost of a bill of soil pipe listed at $100 and subject to a discount of 40 per cent. be desired, find the remaining percentage by subtracting 40 from 100 = 60, and multiply this by the list cost, $100. Thus, $100 x .60 = $60 - net cost of pipe.
In Table XXII will be found the equivalent discounts of well-known and much-used series. In this table not only the equivalent discount of the series is given but also the figures by which to multiply to find the net cost of a bill of goods. For instance, if a bill of goods listed at $100 were subject to a discount of 40, 10 and 5, we have seen that the net cost of the goods would be $51.30. If you now multiply $100 by the factor .513 given in the table, you will see that the same net cost is obtained. The table will be found very convenient when figuring discounts.
Series of discounts not found in the following table can be reduced to their equivalents by the following rule:
10 | and | 5 | equals | 14 1/2% | off list price multiplied by | .855 | = | net cost of goods |
15 | and | 5 | equals | 19 1/4% | off list price multiplied by | .807 | = | net cost of goods |
20 | and | 5 | equals | 24% | off list price multiplied by | .76 | = | net cost of goods |
20 | and | 10 | equals | 28% | off list price multiplied by | .72 | = | net cost of goods |
25 | and | 5 | equals | 28 3/4% | off list price multiplied by | .7125 | = | net cost of goods |
25 | and | 10 | equals | 32 1/2% | off list price multiplied by | .675 | = | net cost of goods |
25, 10, | and | 5 | equals | 35 7/8% | off list price multiplied by | .642 | = | net cost of goods |
30 | and | 5 | equals | 33 1/2% | off list price multiplied by | .665 | = | net cost of goods |
30 | and | 10 | equals | 37% | off list price multiplied by | .63 | = | net cost of goods |
30, 10, | and | 5 | equals | 40 1/7% | off list price multiplied by | .5986 | = | net cost of goods |
35 | and | 5 | equals | 38 1/4% | off list price multiplied by | .6175 | = | net cost of goods |
35 | and | 10 | equals | 41 1/2% | off list price multiplied by | .585 | = | net cost of goods |
35, 10, | and | 5 | equals | 44 2/5% | off list price multiplied by | .556 | = | net cost of goods |
40 | and | 5 | equals | 43% | off list price multiplied by | .57 | = | net cost of goods |
40 | and | 10 | equals | 46% | off list price multiplied by | .54 | = | net cost of goods |
40 10, | and | 5 | equals | 48 7/10% | off list price multiplied by | .513 | = | net cost of goods |
45 | and | 5 | equals | 47 3/4% | off list price multiplied by | .5225 | = | net cost of goods |
45 | and | 10 | equals | 50 1/2% | off list price multiplied by | .495 | = | net cost of goods |
45, 10, | and | 5 | equals | 52 3/40% | off list price multiplied by | .47 | = | net cost of goods |
50 | and | 5 | equals | 52 1/2% | off list price multiplied by | .475 | = | net cost of goods |
50 | and | 10 | equals | 55% | off list price multiplied by | .45 | = | net cost of goods |
50, 10, | and | 5 | equals | 59 1/4% | off list price multiplied by | .4075 | = | net cost of goods |
65 | and | 5 | equals | 57 1/4 % | off list price multiplied by | .4275 | = | net cost of goods |
55 | and | 10 | equals | 59 1/2% | off list price multiplied by | .405 | = | net cost of goods |
55, 10, | and | 5 | equals | 61 1/2% | off list price multiplied by | .385 | = | net cost of goods |
60 | and | 5 | equals | 62% | off list price multiplied by | .38 | = | net cost of goods |
60 | and | 10 | equals | 64% | off list price multiplied by | .36 | = | net cost of goods |
60, 10, | and | 5 | equals | 65 4/5% | off list price multiplied by | .3428 | = | net cost of goods |
65 | and | 5 | equals | 66 3/4% | off list price multiplied by | .3325 | = | net cost of goods |
65 | and | 10 | equals | 68 1/2% | off list price multiplied by | .315 | = | net cost of goods |
65, 10, | and | 5 | equals | 70 7/10% | off list price multiplied by | .293 | = | net cost of goods |
70 | and | 5 | equals | 71 1/2% | off list price multiplied by | .285 | = | net cost of goods |
70 | and | 10 | equals | 73% | off list price multiplied by | .27 | = | net cost of goods |
70, 10, | and | 5 | equals | 74 7/20% | off list price multiplied by | .2565 | = | net cost of goods |
Rule: - To reduce a discount series to an equivalent single discount, subtract each rate of discount from 1, and multiply the remainders together. Subtract the product from 1 and the remainder will be the single discount.
What single discount on the gross price is equivalent to a discount series of 60 per cent., 20 per cent. and 10 per cent.?
1 - .60 = .40; 1 - .20 = .80; 1 - .10 = .90; .40 x .80 x .90 = .288; 1 - .288 - .712, or 71 per cent.
It might be well to point out here that there is a difference between the amounts of discounts expressed for instance, on the one hand, as 40 and 10 and on the other as 50. For example, a $100 bill of goods subject to a discount of 50 per cent. would net $50, while the same bill of goods subject to a discount of 40 and 10 per cent. would cost $54. It will be seen, therefore, that the total discount of a series is always less than the total discount of the sum of all the discounts in a series would be.
 
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