Patterns | Term 1 Chapter 3 | 4th Maths
Chapter: 4th Maths : Term 1 Unit 3 : Patterns
Exercise 3.2b (casting out of nines method)
Text Book Back Exercises Questions with Answers, Solution : 4th Maths : Term 1 Unit 3 : Patterns : Exercise 3.2b (casting out of nines method)
Exercise 3.2b
1. Circle the correct multiplication fact (by using casting out nine method).
a) 312 × 36 = 11232
b) 723 × 24 = 17508
c) 132 × 43 = 5676
a) 312 × 36 = 11232
\( 312 \times \require{cancel} \cancel{36} = \cancel{11232} \)
\( 3+1+2 \times 0 = 0 \)
\( 6 \times 0 = 0 \)
\( 0 = 0 \)
It is correct multiplication fact.
b) 723 × 24 = 17508
\( \require{cancel} \cancel{72}3 \times 24 = \cancel{1}750\cancel{8} \)
\( 3 \times 6 = 7+5+0 \)
\( 18 = 12 \)
\( 9 \neq 3 \)
It is not correct multiplication fact.
c) 132 × 43 = 5676
\( 132 \times 43 = 5676 \)
\( 1+3+2 \times 4+3 = 5 + 6 + 7 + 6 \)
\( 6 \times 7 = 24 \)
\( 42 = 24 \)
\( 6 = 6 \)
It is correct multiplication fact.
2. Circle the correct division fact (by using casting out nine method).
a) 728 ÷ 4 = 182
b) 1580 ÷ 20 = 78
c) 7785 ÷ 9 = 865
a) 728 ÷ 4 = 182
\( \require{cancel} \cancel{72}8 \div 4 = \cancel{18}2 \)
\( 8 \div 4 = 2 \)
\( 8 = 2 \times 4 \)
It is correct division fact.
b) 1580 ÷ 20 = 78
\( 1580 \div 20 = 78 \)
\( [1 + 5 + 8] \div 2 = 7 + 8 \)
\( 14 \div 2 = 15 \)
\( 5 = 15 \times 2 \)
\( 5 = 30 \)
\( 5 = 3 \)
It is not the correct division fact
c) 7785 ÷ 9 = 865
\( 7785 \div 9 = 865 \)
\( 7+ 7 + 8 + 5 = 8 + 6 + 5 \)
\( 27 \div 9 = 19 \)
\( 9 \div 9 = 10 \)
\( 9 = 1 \times 9 \)
\( 9 = 9 \)
It is the correct division fact