NCERT Solutions for Class 4th Maths Chapter 9 Magician Anvi doubles the flowers — The Doubling Magic
Book page 134 Updated on2026-09-19
Q1.
She pulled out 23 flowers, bright and gay! She smiled and said, "Now watch and see, How many flowers will there be?" How many flowers are there now? ______________
Answer
The flowers Anvi pulled out of her coat.
There are 46 flowers now.
The flowers after the magic — two rows just like the first one.
Anvi made one more row exactly like the first row. 23 + 23 = 46 Or 2 × 23 = 46 flowers
Why it happens: Doubling means making two equal groups. Two groups of 23 is the same as 2 × 23.
Q2.
What magic did Anvi do? Complete the table.
Flowers before magic
23
10
51
95
150
199
425
500
Flowers after magic
46
222
410
500
Answer
Flowers before magic
23
10
51
95
150
199
425
500
?
?
?
Flowers after magic
46
?
?
?
?
?
?
?
222
410
500
The table as it is printed in the book.
Anvi’s magic is doubling — she makes every group twice as big.
Before
23
10
51
95
150
199
425
500
111
205
250
After
46
20
102
190
300
398
850
1000
222
410
500
The completed table.
10 + 10 = 20 51 + 51 = 102 95 + 95 = 190 150 + 150 = 300 199 + 199 = 398 425 + 425 = 850 500 + 500 = 1000 For the last three we go backwards (halving): 222 is double of 111 410 is double of 205 500 is double of 250
Tip: To double a number, double the hundreds, the tens and the ones, then add them up. 199 → 200 + 180 + 18 = 398.
Q3.
a) Double of 32 =_____ b) Double of 14 =_____ c) Double of 26 =_____ d) Double of 17 =_____ e) Double of 39 =_____ f) Double of 45 =_____
Why it happens: 26 is 20 + 6. Double the 20 to get 40, double the 6 to get 12, and 40 + 12 = 52.
Q4.
Guess what will be the ones digit of the following numbers when doubled. Write the ones digit in the space provided. a) 28 ______ b) 56 ______ c) 45 ______ d) 17 ______
Answer
Number
Double
Ones digit
28
56
6
56
112
2
45
90
0
17
34
4
Double each number and look at its last digit.
The ones digits are 6, 2, 0 and 4.
Why it happens: Only the ones digit decides the answer. Double 8 is 16 → ones digit 6. Double 6 is 12 → ones digit 2. Double 5 is 10 → ones digit 0.
Q5.
Give examples of numbers that when doubled give the following digits in the ones place. a) 0 _______ b) 2 _______ c) 4 _______ d) 6 _______ e) 8 _______ Can we get 3, 5, 7, 9 as the ones digit after doubling?
Answer
Ones digit wanted
Some numbers that work
Check
0
5, 10, 15, 20, 25
5 → 10, 15 → 30
2
1, 6, 11, 16, 21
1 → 2, 16 → 32
4
2, 7, 12, 17, 22
2 → 4, 17 → 34
6
3, 8, 13, 18, 23
3 → 6, 18 → 36
8
4, 9, 14, 19, 24
4 → 8, 19 → 38
Sample answers — many other numbers also work.
No, we can never get 3, 5, 7 or 9 as the ones digit after doubling.
Why it happens: Doubling makes two equal groups, so the answer is always an even number. Even numbers end only in 0, 2, 4, 6 or 8.
Q6.
What do we notice about the numbers that we get after doubling? Even or Odd?
Answer
Every number we get after doubling is an even number.
2 × 7 = 14 2 × 13 = 26 2 × 25 = 50 14, 26 and 50 all end in 4, 6 and 0 — all even.
Why it happens: A doubled number can be split into two equal groups with nothing left over. That is exactly what an even number is.