B. Change to an improper fraction and multiply by their reciprocal.
1. ) 2 1/10
[tex]2\frac{1}{10} =\frac{10\:\times\:2\:+\:1}{10} =\frac{21}{10}[/tex]
Reciprocal: 10/21
= 21/10 × 10/21
= 210/210
= 1
2. ) 1 7/2
[tex]1\frac{7}{2} =\frac{2\:\times\:1\:+\:7}{2} =\frac{9}{2}[/tex]
Reciprocal: 2/9
= 9/2 × 2/9
= 18/18
= 1
3. ) 3 4/5
[tex]3\frac{4}{5} =\frac{5\:\times\:3\:+\;4}{5} =\frac{19}{5}[/tex]
Reciprocal: 5/19
= 19/5 × 5/19
= 95/95
= 1
4. ) 3 6/9
[tex]3\frac{6}{9}=\frac{9\:\times\:3\:+\;6}{9} =\frac{33}{9}[/tex]
Reciprocal: 9/33
= 33/9 × 9/33
= 297/297
= 1
5. ) 4 2/5
[tex]4\frac{2}{5} =\frac{5\:\times\:4\:+\:2}{5} =\frac{22}{5}[/tex]
Reciprocal: 5/22
= 22/5 × 5/22
= 110/110
= 1
Remember: Any fraction that is multiplied by its reciprocal will always end up with the number 1.
