Question

Explain why or why not 12.702 is a reasonable value for the expression 5.8 ×2.19

Answer 1

5.8 x 2.19

= (5.00 + 0.80) x (2.00 + 0.19)

= 5.00*2.00 + 5.00*0.19 + 0.80*2.00 + 0.80*0.19

= 10.00 + 0.95 + 1.60 + 8/10 * 19/100

= 10.00 + 0.95 + 1.60 + (8*(10+9))/1000

= 10.00 + 0.95 + 1.60 + (80+72)/1000

= 10.00 + 0.95 + 1.60 + 152/1000

= 10.000 + 0.950 + 1.600 + 0.152

= 11.600 + 0.950 + 0.152

= 12.550 + 0.152

= 12.702

It actually is a reasonable value.