Pre-Algebra Demystified

Principles of Borrowing

When the fraction in the subtrahend is larger than the fraction in the

minuend, it is necessary to borrow from the whole number.

When borrowing is necessary, take one (1) away from the whole number,

change it to a fraction with the same numerator and denominator, and then add

it to the fraction.

EXAMPLE

Borrow 1 from 8^15.

SOLUTION

815 ¼ 7 þ 1 þ

1

5

borrow 1 from 8

¼ 7 þ

5

5

þ

1

5

change 1 to

5

5

¼ 765 add

5

5

þ

1

5

EXAMPLE

Borrow 1 from 6^38.

SOLUTION

638 ¼ 5 þ 1 þ

3

8

¼ 5 þ

8

8

þ

3

8

¼ (^5118)
The next examples show how to use borrowing when subtracting mixed
numbers.
EXAMPLE
Subtract 8^25
423 :
SOLUTION
825 ¼ 8156 ¼ (^72115)

423 ¼ 41015 ¼ (^41015)
(^31115)
62 CHAPTER 4 Fractions: Part 2