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NCERT Solutions for Class 7th Maths Chapter 3 In-text Questions — A Hundredth Part

Book page 57 Updated on2026-09-19

Q1.
Are both these methods different?
Answer

No. Method 1 and Method 2 do exactly the same steps — Method 2 just writes them in a column.

StepMethod 1 (expanded)Method 2 (column)
Add each place(15+2) + (3⁄10+6⁄10) + (4⁄100+8⁄100)17 9⁄10 12⁄100
Regroup hundredths17 + 9⁄10 + 1⁄10 + 2⁄10017 10⁄10 2⁄100
Regroup tenths18 + 2⁄10018 2⁄100
Why it happens: both rest on the same two facts — 10 hundredths make 1 tenth, and 10 tenths make 1 unit. Method 1 shows the reasoning; Method 2 is the short form we normally write.
Q2.
Observe the addition done below for 483 + 268. Do you see any similarities between the methods shown above?
(400 + 80 + 3) + (200 + 60 + 8)
= (400 + 200) + (80 + 60) + (3 + 8)
= 600 + 140 + 11
= 600 + 150 + 1
= 700 + 50 + 1
= 751
Page 57 — the addition 483 + 268 as it is worked out in the book.
(a) Method 1
(15 + 2) + (3⁄10 + 6⁄10) + (4⁄100 + 8⁄100)
= 17 + 9⁄10 + 12⁄100
= 17 + 9⁄10 + 1⁄10 + 2⁄100
= 17 + 10⁄10 + 2⁄100
= 18 2⁄100

10 hundredths is the same as 1 tenth.

(b) Method 2
153⁄104⁄100
+26⁄108⁄100
=179⁄1012⁄100
=1710⁄102⁄100
=182⁄100
Page 56 — the two methods shown just above, for the sum 15 3⁄10 4⁄100 + 2 6⁄10 8⁄100.
Answer

Yes — it is the very same procedure, one place value higher.

(400 + 80 + 3) + (200 + 60 + 8)
= 600 + 140 + 11
= 600 + 150 + 1   (10 ones → 1 ten)
= 700 + 50 + 1   (10 tens → 1 hundred)
= 751
Whole numbersDecimal parts
10 ones = 1 ten10 hundredths = 1 tenth
10 tens = 1 hundred10 tenths = 1 unit
Add ones first, carry leftAdd hundredths first, carry left
Why it happens: in the Indian place value system every place is 10 times the place on its right — and that stays true when we walk right of the units place into tenths and hundredths. So the same carrying rule works everywhere.
Q3.
What is the difference: 25 9/10 – 6 4/10 7/100 ?
Answer

The first number has no hundredths, so open one tenth into 10 hundredths first.

25 9⁄10 = 25 8⁄10 10⁄100
Hundredths: 10 – 7 = 3
Tenths: 8 – 4 = 4
Units: 25 – 6 = 19
= 19 4⁄10 3⁄100  (that is, 19.43)
Why it happens: 25 9⁄10 means 25 units, 9 tenths and 0 hundredths. Since 7 hundredths cannot be taken from 0, one of the 9 tenths is exchanged for 10 hundredths, leaving 8 tenths and 10 hundredths.
Check it yourself: 19.43 + 6.47 = 25.90 ✓
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