it means multiply the the number in the ones place by two and use that number to subtract
The number must meet two criteria:Take the original number excluding its last digit and subtract two times the last digit from it. The result must be divisible by 7.Take the original number excluding its last digit and subtract nine times the last digit from it. The result must be divisible by 13.In both cases, you can repeat the "truncate-and-subtract multiple" stage several times, if required.
Double the last digit and subtract the last digit from the remaining digits.
9,000,0009,999,999 is the last 7 digit number1,000,000 is the first 7 digit numberwhen you subtract the first from the last and add one you get the above answer.
Subtract 5 times the last digit from remaining truncated number. Repeat the step as necessary. If the result is divisible by 17, the original number is also divisible by 17
To discover whether a number is divisible by 7, double the last digit of the number, and subtract it from the rest of the number. If the result is either 0 or divisible by 7, then the number is divisible by 7. For example:672 - last digit is 2, double 2 to make 4, subtract from 67 equals 63, 63/7 = 9, therefore, 672 is divisible by 7.Dividing by 7 (2 Tests)Take the last digit in a number.Double and subtract the last digit in your number from the rest of the digits.Repeat the process for larger numbers.Example: 357 (Double the 7 to get 14. Subtract 14 from 35 to get 21 which is divisible by 7 and we can now say that 357 is divisible by 7. NEXT TESTTake the number and multiply each digit beginning on the right hand side (ones) by 1, 3, 2, 6, 4, 5. Repeat this sequence as necessaryAdd the products.If the sum is divisible by 7 - so is your number.Example: Is 2016 divisible by 7?6(1) + 1(3) + 0(2) + 2(6) = 2121 is divisible by 7 and we can now say that 2016 is also divisible by 7.
The number must meet two criteria:Take the original number excluding its last digit and subtract two times the last digit from it. The result must be divisible by 7.Take the original number excluding its last digit and subtract nine times the last digit from it. The result must be divisible by 13.In both cases, you can repeat the "truncate-and-subtract multiple" stage several times, if required.
Subtract nine times the last digit from the rest; repeat if necessary. The result must be divisible by 13.
Double the last digit and subtract the last digit from the remaining digits.
9,000,0009,999,999 is the last 7 digit number1,000,000 is the first 7 digit numberwhen you subtract the first from the last and add one you get the above answer.
you take the last digit in the first one and add/subtract it to the last digit in the second one and that is your answer
Yes. 7 - 2 is 5, and if the last digit on one number is 7 and the last digit on one you are subtracting from it is 2, the last digit on the answer will be a 5. That will help you in doing estimations.
Subtract 5 times the last digit from remaining truncated number. Repeat the step as necessary. If the result is divisible by 17, the original number is also divisible by 17
208
Double the last digit. Subtract it from the rest. If the result is divisible by 7, the original number is divisible by 7.
To discover whether a number is divisible by 7, double the last digit of the number, and subtract it from the rest of the number. If the result is either 0 or divisible by 7, then the number is divisible by 7. For example:672 - last digit is 2, double 2 to make 4, subtract from 67 equals 63, 63/7 = 9, therefore, 672 is divisible by 7.Dividing by 7 (2 Tests)Take the last digit in a number.Double and subtract the last digit in your number from the rest of the digits.Repeat the process for larger numbers.Example: 357 (Double the 7 to get 14. Subtract 14 from 35 to get 21 which is divisible by 7 and we can now say that 357 is divisible by 7. NEXT TESTTake the number and multiply each digit beginning on the right hand side (ones) by 1, 3, 2, 6, 4, 5. Repeat this sequence as necessaryAdd the products.If the sum is divisible by 7 - so is your number.Example: Is 2016 divisible by 7?6(1) + 1(3) + 0(2) + 2(6) = 2121 is divisible by 7 and we can now say that 2016 is also divisible by 7.
Double the last digit, subtract it from the rest. If the result is divisible by 7, the whole number is divisible by 7.
If you double the last digit and subtract it from the rest of the number and the answer is zero or divisible by 7, then the whole number is divisible by 7.