For example, 168,293 is divisible by 1, since 1×168,293=168,293{\displaystyle 1\times 168,293=168,293}.

Remember that 0 is an even number. [3] X Research source

You can repeat the addition of digits if the original sum is too long for you to gauge divisibility by 3. [5] X Research source For example, the digits in 3,989,978,579,968,769,877 add up to 141. You can then add again: 1+4+1=6{\displaystyle 1+4+1=6}. Since 6 is divisible by 3, you know the entire number is divisible by 3.

Another way to check for divisibility by 4 is to divide the number by 2 twice. If the quotient is still a whole number, the original number is divisible by 4. [8] X Research source For example, 8762=438{\displaystyle {\frac {876}{2}}=438}, and then 4382=219{\displaystyle {\frac {438}{2}}=219}. Since 219 is a whole number, you know that 876 is divisible by 4.

For example, to find out if 567 is divisible by 7, first separate the last digit from the number. This gives you 56 and 7. Double the last digit, 7: 7×2=14{\displaystyle 7\times 2=14}. Then, subtract 14 from 56: 56−14=42{\displaystyle 56-14=42}. Since 42 is divisible by 7, you know that 567 is divisible by 7.

Another way to do this is to halve the last three digits 3 times. If the final quotient is a whole number, then the entire number is divisible by 8. [13] X Research source For example, 1282=64{\displaystyle {\frac {128}{2}}=64}, then 642=32{\displaystyle {\frac {64}{2}}=32}, then 322=16{\displaystyle {\frac {32}{2}}=16}. Since 16 is a whole number, you know that the number 11,128 is divisible by 8.

If, after adding up the sum of all the component parts of a number which comes out to another two digit or bigger number the sum is exposed, take that number and add it’s component parts. (Take for example 189: 1+8+9=27. . . if you then take 2+7 you will get 9. Therefore, 189 is evenly divisible by 9. ) You can repeat the addition of digits if the original sum is too long for you to gauge divisibility by 9. [15] X Research source For example, the digits in 3,989,978,579,968,769,877 add up to 141. You can then add again: 1+4+1=6{\displaystyle 1+4+1=6}. Since 6 is not divisible by 9, you know the entire number is not divisible by 9.

The test for determining whether a number is divisible by 6 is twofold. First determine whether the number is even. 456 is even, since it ends in 6. Then, determine whether the sum of the digits is divisible by 3. So, you would calculate 4+5+6=15{\displaystyle 4+5+6=15}. The number 15 is divisible by 3. Since 456 passes both tests, it is divisible by 6.

1 divides evenly into the number, since any number is divisible by 1. 2 divides evenly into the number, since 1,336 is even. 3 does not divide evenly into the number, since the sum of its digits is 13, and 13 is not divisible by 3. 4 divides evenly into the number, since the last two digits, 36, is divisible by 4. 5 does not divide evenly into the number, since 1,336 does not end in 5 or 0. 6 does not divide evenly into the number. While it is an even number, the sum of its digits is not divisible by 3. 7 does not divide evenly into the number. When you double the last digit (6), and subtract it from the remaining digits, you get 133−12=121{\displaystyle 133-12=121}. Since 121 is not divisible by 7, neither is 1,336. 8 divides evenly into the number, since the last three digits, 336, is divisible by 8. 9 does not divide evenly into the number, since the sum of its digits is 13, and 13 is not divisible by 9.

He cannot evenly divide the crayons among the four groups. 363 is not divisible by 4, since it is not an even number, and since the number made from the last two digits, 63, is not divisible by 4.