Worksheet on Computation Operations for Class 4

1. Evaluate: {2 × 42 ÷ 3 × 5} + 16

a) 136
b) 146
c) 156
d) 166

Answer: c) 156

Explanation: Use BODMAS rule,

{2 × 42 ÷ 3 × 5} + 16

= {2 × (42 ÷ 3) × 5} + 16
= {2 × 14 × 5} + 16
= 140 + 16
= 156

2. Simplify the expression: 19 − 4 + 8 × 6 ÷ 3

a) 13
b) 26
c) 30
d) 31

Answer: d) 31

Explanation: Use BODMAS rule,

19 − 4 + 8 × 6 ÷ 3 

= 19 − 4 + 8 × (6 ÷ 3)
= 19 − 4 + 8 × (2)
= 19 − 4 + 16
= 19 + 16 − 4
= 35 − 4
= 31

3. If the cost of 25 jackets is $4000, what will be the cost of 8 jackets?

a) $1080 
b) $1180
c) $1280
d) $1380

Answer: c) $1280

Explanation: Cost of 25 jackets = $4000
Cost of 1 jacket = $(4000 ÷ 25)
Cost of 8 jackets = (4000 ÷ 25) × 8 [Using BODMAS rule]
= 160 × 8 
= $1280

4. The total number of students in each section is 45. There are six sections. What is the total number of boys if the total number of girls is 142?

a) 108
b) 118
c) 128
d) 138

Answer: c) 128

Explanation: Total number of students in all the sections = 45 × 6
Total number of girls = 142
Total number of boys = (45 ×  6) − 142 [Using BODMAS rule]
= 270 − 142
= 128

5. The price of three dozen eggs is $72. If six eggs are rotten, what is the price of healthy eggs?

a) $30 
b) $45
c) $60 
d) $90

Answer: c) $60 

Explanation: 1 dozen = 12
3 dozen = 3 × 12
Price of three dozen (3 × 12) eggs = $72
Price of 1 egg = ${72 ÷ (3 × 12)}
Number of rotten eggs = 6
Number of healthy eggs = 36 − 6 = 30
Price of 30 eggs = {72 ÷ (3 × 12)} x 30 [Using BODMAS rule]
= {72 ÷ (36)} x 30
= (2 × 30)
= $60

OR

3 dozen = 3 × 12 eggs
Price of three dozen (36) eggs = $72
Price of 1 egg = $(72 ÷ 36) = $2
Number of rotten eggs = 6
Number of healthy eggs = 36 − 6 = 30 eggs
Price of 30 eggs = 2 × 30 = $60