Question

use rules of divisibility to determine whether each number given in exercises 1-10 is divisible by
a. 2 b. 3 c.4 d.5 e.6 f.8 g.9 h.10 i.12

1. 6944 2. 7245 3. 21,408 4. 25,025 5.26,428 6. 89,001 7. 374,832 8. 347,712 9. 6,126,120 10. 5,941,221

Answer 1

the last digit of the number is even, that number can divided by 2. EX: 6944; the last digit is 4; 4 is even ----> the whole number 6944 is divided by2
the sum of digits in a number can be divided by 3 ---> the whole number can be divided by 3. EX: 7245 the sum of them is 7+2 +4 +5 = 18 and then 18 = 1 + 8 = 9 ; 9 is divided by3 . So, the whole thing is 7245 is divided by 3
the last digit of the number is 0 or 5, that number is divided by 5. EX: 6,126,120 the last digit is 0 ---> 6,126120 is divided by 5
the last digit of a number is 0 ( just 0, not 5 like above) that number is divided by 10. EX: is the same as above.

Answer 2

a number can be divided by 2 and by 3 at the same time, it is divided by 6 . EX: 374832 has the last digit is 2, it is even ---> the whole number is divided by 2. On the other hand, sum of them is 3 + 7 + 4 +8 +3 + 2 =27 and then 2+7 = 9 , 9 is divided by 3 ---> the whole 374832 is divided by 3
it is divided by both 2 and 3 ---> it is divided by 6

Answer 3

Hope this help

Answer 4

at divisibility by 4: just consider the number formed by the last two digits. If it's divisible by 4, then the whole number is also divisible by 4.

divide the red number by 4
\[15\color{red}{72}\rightarrow \color{red}{72} \div 4 = 18\]

divisibility by 8: the number formed by the last three digits is divisible by 8 if the whole number is divisible by 8.
divide the number in red by 8
\[53\color{red}{104}\]