alleryStart learning →Is 645 divisible by 3, using the divisibility test based on the sum of its digits?
ANo, because 15 is not divisible by 3
BYes, because 645 ends in the digit 5
CYes, because 15 is divisible by 3
DNo, because 645 is an odd number
Answer & Solution
Correct answer: C. Yes, because 15 is divisible by 3
1. The divisibility test for 3 checks whether the sum of the digits is divisible by 3.
2. Add the digits of 645: 6 plus 4 plus 5 equals 15.
3. Since 15 is divisible by 3, the number 645 is divisible by 3 as well.
4. The last digit of a number tells you about divisibility by 2, 5, or 10, not divisibility by 3, so the ending digit is not the correct reason.
_Source: OpenStax Prealgebra (CC BY 4.0), Ch 2 "The Language of Algebra", section 2.4 Find Multiples and Factors_
Keep practising The Language of Algebra
Browse all The Language of Algebra questions for Key Stage 3 (KS3), or explore more Mathematics topics.
Related questions
Complete the number line rulePick the number line fact, fastThe number 1 has only one factor, itself. Where does 1 fit among prime and composite numbeA prime number is a counting number greater than 1 with what property regarding its factorIf two counting numbers a and b multiply to give m, what are a and b called?Using the divisibility test for 2, which digit in the ones place tells you a number is divA number is a multiple of n when it fits which description?Solve the equation 100 equals y plus 74.