Page 73 - Start Up Mathematics_4

2. Find the product of 14 and 17.

3. Use the simple trick to find the products.

(a) 8 × 10 (b) 13 × 15 (c) 23 × 25
4. Multiply 526 and 4,615 by 11 using addition.

Solving Word Problems

Example 14: A pet store has 15 tanks of tadpoles. If each tank has 46
tadpoles, how many tadpoles does the pet store have? Working
3
Solution: Number of tadpoles in 1 tank = 46 4 6
Number of tanks = 15 × 1 5
2 3 0
Number of tadpoles in 15 tanks = 46 × 15 = 690 + 4 6 0

Thus, there are 690 tadpoles in the tanks. 6 9 0

Framing Word Problems

Example 15: Frame two word problems for 3,432 × 6.

Solution: 1. A baker sells 3,432 loaves of bread in a week. How many loaves does he
sell in 6 weeks?
2. A typist types 3,432 words in a day. How many words does he type in
6 days?

Mixed Problems

Example 16: Simplify 20 × 6 – 16 × 2 + 4 × 5. Remember
In sums which have
Solution: 20 × 6 – 16 × 2 + 4 × 5 (multiply) addition, subtraction
= 120 – 32 + 20 (put numbers with the and multiplication, we
same signs together) first multiply, then add
= 120 + 20 – 32 (add) and lastly subtract.

= 140 – 32 (subtract)
= 108

Example 17: A factory has 1,563 workers. There are 80 factory vans. If 8 workers come in
each van, how many people come by other means of transport?

Solution: Number of vans = 80
Number of workers in each van = 8

Workers travelling by vans = 80 × 8 = 640
Total number of workers = 1,563
Workers travelling by other transport = 1,563 – 640 = 923

So, 923 workers travel by other means of transport.

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