Q1.
What will be the sum of 15 3/10 4/100 and 2 6/10 8/100 ?
Answer
Units: 15 + 2 = 17
Tenths: 3 + 6 = 9
Hundredths: 4 + 8 = 12
= 17 + 9⁄10 + 12⁄100
12 hundredths = 1 tenth + 2 hundredths
= 17 + 9⁄10 + 1⁄10 + 2⁄100
= 17 + 10⁄10 + 2⁄100
= 18 2⁄100 (that is, 18.02)
Tenths: 3 + 6 = 9
Hundredths: 4 + 8 = 12
= 17 + 9⁄10 + 12⁄100
12 hundredths = 1 tenth + 2 hundredths
= 17 + 9⁄10 + 1⁄10 + 2⁄100
= 17 + 10⁄10 + 2⁄100
= 18 2⁄100 (that is, 18.02)
Working entirely in hundredths gives the same answer:
1534⁄100 + 268⁄100 = 1802⁄100 = 1800⁄100 + 2⁄100 = 18 2⁄100
Why it happens: two regroupings take place. First 12 hundredths become 1 tenth and 2 hundredths; then the 10 tenths become 1 whole unit, pushing 17 up to 18.