how many positive even integers less than 100 contain digits 3 or 9 ?
"two digit numbers : 3 at tens place : 30 , 32,34 , 36,38 9 at tens place : 90 , 92,94 , 96,98 if 3 and 7 is at units place , the number cant be even total : 5 + 5 = 10 answer e"
multiply(3, const_2)