DIVISIBILITY RULES
A number is divisible by 2 if it ends in these digits.
0, 2, 4, 6, or 8
A number that has only two factors, 1 and itself, is called?
a prime number
Multiply: 0.5 × 4.
Answer: 2
Divide: 4.8 ÷ 2.
Answer: 2.4
If a number ends with O and 5?
It is divisible by 5.
A composite number is a number that...?
A number that has more than two factors.
Multiply: 0.3 × 5.
Answer: 1.5
Divide: 3.6 ÷ 3.
Answer: 1.2
Is 123 divisible by 3? Explain using the rule.
Yes because 1+2+3=6, since 6 is divisible by 3 then 123 is divisible by 3)
Is the number 7 prime or composite? Explain.
It's a prime because it only has two factors, 1 and 7.
Multiply: 0.6 × 0.2.
Answer: 0.12
Before dividing decimals, why do we have to move the decimal point to the right?
To make the divisor a whole number.
A number is divisible by 6 if it is divisible by these two numbers.
2 and 3
Name all the factors of 12 to show it is composite.
1, 2, 3, 4, 6, and 12?
Multiply: 1.25 × 0.4.
Answer: 0.50 or 0.5
Divide: 6.4 ÷ 0.8.
Answer: 8
Is 2,736 divisible by 9? Explain using the rule.
Yes because 2+7+3+6 = 18, and 18 is divisible by 9
Explain why 1 is neither prime nor composite.
It has only one factor, not two or more.
What is the rule for placing the decimal point when multiplying decimals?
Count the decimal places in the numbers you multiply, then put the decimal in the answer with the same total number of places.
Divide: 7.5 ÷ 0.5.
Answer: 15