Page 63 - Math Genius C2

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5. t O t O 6. t O t O

5 1 5 6
– 2 7 + – 3 8 +

RelATION BeTWeeN ADDITION AND SUBTRACTION

There is a special relationship between addition and subtraction facts. This

relationship can be seen in fact families. A fact family is a set of facts with the same
three numbers. Look at the collection of stars.

In the following fact family, all four facts have the numbers 6, 9 and 15.

t O t O t O t O

6 9 1 5 1 5
+ 9 + 6 – 9 – 6
1 5 1 5 6 9

There are 18 caps. Out of these, 12 are green and 6 are red.

Knowledge Desk

Did you know that a
Let us write the fact family for 6, 12 and 18. woman's heart generally

t O t O t O t O beats faster than a man’s?

1 2 6 1 8 1 8 A woman's heart beats 82
times per minute, while a
+ 6 + 1 2 – 1 2 – 6 man's beats 78 times.
1 8 1 8 6 1 2

Practice Time 3e

Write the fact family for each group of numbers.

1. 5, 6, 11 2. 9, 12, 21 3. 17, 21, 38

+ = + = + =

+ = + = + =

– = – = – =

– = – = – =

Mathematics-2 61