Four prime numbers are arranged in ascending order. The product of first three numbers is 255 and the product of last three numbers is 1955. The largest prime number is

Four prime numbers in ascending order.
Product of first three = 255
Product of last three = 1955

Largest prime = (product of last three) ÷ (product of middle two)

255 = 17 × 15
15 = 3 × 5
So the first three primes (in ascending order) are:
3, 5, 17

Thus, the middle two primes are 5 and 17, and their product is:
5 × 17 = 85

Largest prime = 1955 ÷ 85

Check:
85 × 23 = 1955

So the largest prime is 23.