My question is about estimaing products

Examples: 1/5 x 26; 1/3 x 4/11; and 4 1/3 x 3 7/8. i can't remember how to multiply these types of problems let alone,estimate the products. Can u please help me to help my son.

1/5 x 26.

That's about 25/5 = about 5.

1/3 x 4/11.
That's 1 x 4 = 4 for the numerator.
3 x 11 = 33 for the denominator.
4/33 = about 4/32 = about 1/8

4 1/3 x 3 7/8.
That's about 4 x 4 = about 16.