18 × 5 = 90. The five children in the book each found it a different way, and all five are right. Child's method The working Answer Halve 18, then double the answer 9 × 5 = 45, and 45 + 45 90 Double, double, then add one more 18 + 18 = 36, 36 + 36 = 72, 72 + 18 90 Split 18 into 10 and 8 10 × 5 = 50, 8 × 5 = 40, 50 + 40 90 Doubling and halving 18 × 5 = 9 × 10 90 Nearest multiple 20 × 5 = 100, take away 2 × 5 = 10 90 The easiest one to do in your head Step 1. Half of 18 is 9. Step 2. Double of 5 is 10. Step 3. 9 × 10 = 90 Try this: Cover the table and find 18 × 5 in a sixth way of your own. For example, 18 × 5 is half of 18 × 10, and 18 × 10 = 180, so the answer is 90.

NCERT Solutions for Class 5th Maths Chapter 6 Five children find 18 × 5

Q1.

What is 18 × 5?

Answer

18 × 5 = 90.

The five children in the book each found it a different way, and all five are right.

Child's method	The working	Answer
Halve 18, then double the answer	9 × 5 = 45, and 45 + 45	90
Double, double, then add one more	18 + 18 = 36, 36 + 36 = 72, 72 + 18	90
Split 18 into 10 and 8	10 × 5 = 50, 8 × 5 = 40, 50 + 40	90
Doubling and halving	18 × 5 = 9 × 10	90
Nearest multiple	20 × 5 = 100, take away 2 × 5 = 10	90

The easiest one to do in your head
Step 1. Half of 18 is 9.
Step 2. Double of 5 is 10.
Step 3. 9 × 10 = 90

Try this: Cover the table and find 18 × 5 in a sixth way of your own. For example, 18 × 5 is half of 18 × 10, and 18 × 10 = 180, so the answer is 90.

Q2.

Do you think they are all correct? Why do you think so?

Answer

Yes, all five are correct. Every one of them ends at 90, and each one is built on a rule we can trust.

Halving and doubling back. 9 is half of 18, so 9 × 5 is half the answer. Adding it twice gives the whole answer. 45 + 45 = 90 ✓
Doubling twice and adding one more group. Two 18s, then four 18s, then one more 18 makes five 18s. 36, 72, then 72 + 18 = 90 ✓
Splitting 18 into 10 and 8. Five groups of 18 is the same as five groups of 10 plus five groups of 8. 50 + 40 = 90 ✓
Doubling one and halving the other. Halve 18 to 9 and double 5 to 10. 9 × 10 = 90 ✓
Going to the nearest multiple. Five 20s is 100. But we only wanted five 18s, which is five 2s less. 100 − 10 = 90 ✓

Why they must all agree: The question never changed — it is still five groups of 18 packets. The children only chose different ways to count the same packets. Different roads, same destination.

Sample answer for the class discussion: All the methods are correct because none of them adds anything or takes anything away without putting it back. The method you pick can depend on the numbers. For 18 × 5, doubling and halving is fastest, because it turns a hard 5 into an easy 10.

NCERT Solutions for Class 5th Maths Chapter 6 Five children find 18 × 5 — Many Ways to Multiply