Page 71 - Start Up Mathematics_3

H T O

3 4 Step 2: Multiply the multiplicand by the digit in
the tens place of the multiplier.
× 2 0
34 × 2 tens = 32 × 20 = 680
6 8 0

H T O

3 4 Step 3: Add the two products obtained in step 1

× 2 5 and 2.

1 1 7 0

+ 6 8 0

8 5 0

So, 34 × 25 = 850.

Shortcut method of multiplying a 2-digit number by a 1-digit number

Example 6: Find 47 × 8.

Solution: Break 47 into 40 and 7 such that 40 + 7 = 47.

Multiply 40 and 7 separately by 8. Remember

40 × 8 = 320 7 × 8 = 56 This method is known
Add the two products to get the answer. as expanded notation
method.
320 + 56 = 376

So, 47 × 8 = 376.

EXERCISE 5.4

1. Fill in the empty boxes.

(a) 28 × 10 = (b) 146 × 10 = (c) 59 × 100 =

(d) 312 × 100 = (e) 77 × 1000 = (f) 892 × 1000 =

(g) 64 × = 6400 (h) 187 × = 1870 (i) 390 × 10 =

(j) 564 × = 564000 (k) × 100 = 92000 (l) 931 × 100 =

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