7 is the number that can go into both 35 and 49.
1, 5, 7, 35.
315
140
1 and 7 both can.
The only number that can go into both numbers is 5
1
The only number that goes into both 39 and 100 evenly is the number one.
Only the number one (1) goes into both 100 and 31 evenly.
No - 100/35 = 2.857142 recurring (that is, 2.857142857142...)
The HCF of both numbers is 1
35 is an odd number, so no even number can go into it.