Suppose the mass of a dog is 90 pounds. If 1 kilogram is equal to 2.2 pounds, what is the mass of the dog in kilograms?

##=41## kg (rounded to two significant digits).

This problem is of "Unitary method". It is always a good idea to keep the the asked quantity towards the right side of = sign.

2.2 pounds of mass = 1 kg 1 pound of mass = ##1/2.2## kg 90 pounds of mass = ##1/2.2 xx 90## kg ##=40.dot 9 dot 0## kg

Using the rule for rounding off for multiplication or division. We observe that in the given numbers there are 2 least significant digits. ##=41## kg (rounded to two significant digits).