Whenever Jasoda has to subtract 9 from a number, she subtracts 10 and adds 1 to it. Class 7

Whenever Jasoda has to subtract 9 from a number, she subtracts 10 and adds 1 to it. Class 7

Question 1.

Whenever Jasoda has to subtract 9 from a number, she subtracts 10 and adds 1 to it. For example, 36 - 9 = 26 + 1. Class 7

(a) Do you think she always gets the correct answer? Why?

(b) Can you think of other similar strategies? Give some examples.

Solution:

(a) Yes, because -10 + 1 = -9.

(b) Do as directed. For example, to subtract 8, subtract 10 and add 2. 

Question 2.

Consider the two expressions :

(a) 73 - 14 + 1, (b) 73 - 14 - 1. For each of these expressions, identify the expressions from the following collection that are equal to it. Class 7

(a) 73 - (14 + 1)

(b) 73 - (14 - 1)

(c) 73 + (- 14 + 1)

(d) 73 + (- 14 - 1)

Solution:

(a) For this expression, the expression 73 - (14 - 1) (t.e., (b)) is equal. The expression 73 + (-14 + 1) (c) is also equal to it.

(b) For this expression, the expression 73 - (14 + 1) (a) and 73 + (-14 - 1) (d) are equal.

Question 3.

If another friend, Sangmu, joins them and orders the same items, what will be the expression for the total amount to be paid? Class 7

Solution:

Total amount = 3 × (43 + 24) = 3 × 43 + 3 × 24.