The result of multiplying numbers is called the product. The multiplication sign (x) tells you have to multiply. Multiplication is a short method for adding equal amounts. For example, 4 times 5 (4 x 5) means 4 fives or 5 + 5 + 5 + 5.
Numbers can be multiplied in any order. The same product is obtained regardless of whatever order the numbers are multiplied. For example:
4 x 3 = 3 x 4.
This is called the commutative property of multiplication.
The total cost of fixtures and lights for an office lighting installation is found by an electrician. The following fixtures and lights are:
Find the total cost.
Answer
Work out the process
Multiply the required number of each light or fixture by the cost of each. The total cost is the sum of the products.
Estimate the answer
Total cost = (10 x $20) + (20 x $40) + (30 x $30)
= $200 + $800 + $900
= $1900
Work out the answer
Total cost = (12 x $18) + (22 x $37) + (33 x $28)
= $216 + $814 + $924
= $1954
Check the answer to the estimate
$1954 is about the same as $1900.
The WelTec calculator Company makes five models of calculator. The following data gives the weekly (5 –day) production output.
Model Alpha Beta Gamma Delta Tau
Cost $8 $19 $35 $52 $182
Number 121 72 28 39 19
Find the weekly (5-Day) production cost.
Answer
Alpha = 121 x 8 = 968 Beta = 72 x 19 =1368
Gamma = 35 x 28 =980 Delta = 52 x 39 = 2028
Tau = 182 x 19 = 3458
Total Production Cost = 968 + 1368 + 980 + 2028 + 3458
= $ 8802