Multiplying by 10 and 100

In your book, Maths Mela (Chapter 13, The Transport Museum), we multiply by 10 by counting tens. 2 × 10 means 2 groups of 10, which is 2 tens, or 20. 5 × 10 is 5 tens = 50, and 8 × 10 is 8 tens = 80.

What about 10 × 10? That is 10 tens, and 10 tens make 1 hundred. So 10 × 10 = 100. Now 14 × 10 is 14 tens. That is 10 tens and 4 tens, which is 100 + 40 = 140.

A tempo traveller can carry 10 people. How many people can travel in 26 tempo travellers? 26 × 10 = 26 tens = 20 tens + 6 tens = 200 + 60 = 260 people. In the same way, 87 × 10 = 87 tens = 870.

We multiply by 100 by counting hundreds. 2 × 100 = 2 hundreds = 200. 10 × 100 is 10 hundreds, and 10 hundreds make 1000. So 11 × 100 = 11 hundreds = 1000 + 100 = 1100, and 27 × 100 = 27 hundreds = 2700.