What is the greatest prime factor of 78? Prealgebra Factors and Multiples Prime Factorization 1 Answer Shwetank Mauria Dec 25, 2016 #13# is the greatest prime factor of #78#. Explanation: Last digit of #78# is #8#, an even number and hence divisible by #2#. Further, sum of the digits is #7+8=15#, divisible by #3#. Hence #78# is divisible by prime numbers #2# ad #3#. Dividing #78# by these numbers, we get #13# and hence #78=2xx3xx13# Hence, #13# is the greatest prime factor of #78#. Answer link Related questions What is the prime factorization of 828? What is the prime factorization of 26? What is the prime factorization of 84? What is the prime factorization of 38? What is the prime factorization of 90? How do you use prime factorization? How do you make a prime factorization tree? How do you find the prime factorization of 20? How do you find prime factorization of a number? What is the prime factorization of 44? See all questions in Prime Factorization Impact of this question 6870 views around the world You can reuse this answer Creative Commons License