Page 75 - Start Up Mathematics_4

Example 18: Multiply 345 and 15 using lattice multiplication.

Solution: Step 1: Write the numbers you’re
multiplying along the top and
side of the grid. 3 4 5
0 0 0
Step 2: Multiply the single digits on
the top by the single digits on 3 4 5 1
the side to fill in the squares. 1 2 2
The tens digit of the product is 5 0 5 5
written above the slanting line
5 + 2 + 4 = 1 1
and the ones digit is written 1 + 1 + 3 = 5 2 + 5 = 7 5
below the line. If the product
is a single-digit number, write
0 above the slanting line and
the number below the line.
Step 3: Add diagonally to find your answer. Carry double digit sums to the
next place.
Step 4: Start writing the answer from the left and move till the last digit.

So, 345 × 15 = 5,175.
1 4 5

0 1 2 4
Example 19: Multiply 145 and 415 using lattice 4 6 0
multiplication. 0 0 0 1

Solution: 145 × 415 = 60,175 0 1 2 4 2 5 5
1 + 4 + 1 = 6 5 + 2 + 4 = 1 1 5 0 5 5
1 + 1 + 6 + 2 = 1 0
2 + 5 = 7

EXERCISE 5.10

1. Multiply by lattice multiplication.

(a) 355 × 18 = _____________ (b) 668 × 92 = _____________

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