Divisibility Rule of 8: Rules, Tricks and Examples
Divisibility Rule of 8 determines whether a number can be divided by 8 without leaving a remainder. For numbers with three or more digits, check only the last three digits. This page explains the divisibility by 8 rule, its mathematical basis, quick calculation methods and solved examples.
What Is the Divisibility Rule of 8?
This rule works because 1000 is divisible by 8. If a number is written as N = 1000q + r, where r is its last three-digit part, then N and r have the same remainder when divided by 8. Therefore, 5,216 is divisible by 8 because its last three digits, 216, are divisible by 8: 216 ÷ 8 = 27.
Divisibility Rule of 8 Formula & Tricks
Important Formulas
Here, r represents the last three digits of N. Since 1000 mod 8 = 0, only r determines divisibility by 8.
The last three-digit part may include leading zeroes, such as 016 or 008.
Quick Tricks
Ignore all digits before the last three digits. Divide the remaining three-digit number by 8 or compare it with a nearby multiple of 8.
If direct division is inconvenient, find whether the last three digits equal 8 times an integer.
Divisibility Rule of 8 Concepts
Testing a Three-Digit or Larger Number
The digits before the final three do not affect divisibility because every multiple of 1000 is also a multiple of 8. Thus, for 12,344, test 344 rather than the complete number. Since 344 ÷ 8 = 43, 12,344 is divisible by 8.
Testing Numbers with Fewer Than Three Digits
The two-digit multiples of 8 include 16, 24, 32, 40, 48, 56, 64, 72, 80 and 88. Therefore, 72 is divisible by 8, while 74 is not because 74 ÷ 8 leaves a remainder of 2.
Using Leading Zeroes in the Last Three Digits
For example, the last three digits of 7,016 are 016, which has the same value as 16. Since 16 is divisible by 8, 7,016 is divisible by 8. Similarly, 9,008 is divisible by 8 because 008 equals 8.
Finding the Remainder When Dividing by 8
Write N = 1000q + r. Since 1000q is divisible by 8, the remainder of N depends only on r. For 4,219, the last three digits are 219; 219 = 8 × 27 + 3, so the remainder is 3.
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Divisibility Rules for 2, 4 and 8
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Divisibility Rule of 8: Quick Revision
Use the final three digits to test divisibility by 8.
- A number is divisible by 8 when its last three digits are divisible by 8.
- For numbers with fewer than three digits, test the complete number.
- The rule follows from 1000 = 8 × 125.
- Leading zeroes may be added to make the final part three digits, such as 16 becoming 016.
- For N = 1000q + r, N and r have the same remainder when divided by 8.
- If the last three digits leave a non-zero remainder on division by 8, the complete number is not divisible by 8.
Divisibility Rule of 8 FAQs
What is the divisibility test for 8?
A number is divisible by 8 if its last three digits form a number divisible by 8. If the number has fewer than three digits, test the whole number.
Why are only the last three digits checked for divisibility by 8?
Because 1000 = 8 × 125, every place-value part before the last three digits is divisible by 8. Hence, only the final three-digit part affects the remainder.
Is 12,016 divisible by 8?
Yes. Its last three digits are 016, which equals 16, and 16 ÷ 8 = 2.
Is 5,734 divisible by 8?
No. Its last three digits are 734. Since 8 × 91 = 728 and 8 × 92 = 736, 734 is not divisible by 8.
What is the remainder when 27,451 is divided by 8?
Check 451. Since 451 = 8 × 56 + 3, the remainder is 3.
Are numbers ending in 000 always divisible by 8?
Yes, provided the number is an integer. Its last three digits are 000, and 0 is divisible by 8; for example, 14,000 ÷ 8 = 1,750.
