Question

Naomi’s fish is 40 millimetres long. Her guinea pig is 25 cm long. How much longer is her guinea pig than her fish?

Answer 1

Hint: We use the concept of larger and lesser valued numbers. We equate the measurement unit of the length of the fish and the guinea pig. Then using the operation of subtraction, we find the value of the difference.

Complete step-by-step solution:
We need to find the difference between the length of Naomi’s fish and her guinea pig.
The difference of length has to be positive. Therefore, the difference will be calculated by subtracting the length with lesser value from the length with larger value.
Naomi’s fish is 40 millimetres long. Her guinea pig is 25 cm long.
We know that to measure the length all the units have to be similar to compare them.
Therefore, we will change the length of the guinea pig from centimetres to millimetres.
We know the relation that 1 centimetre is equal to 10 millimetres.
Therefore, the length of the guinea pig is $25\times 10=250$ millimetres.
Obviously $250>40$ which gives that the guinea pig is longer than the fish.
The guinea pig is longer than the fish by $250-40=210$ millimetres.
It is also equal to $\dfrac{210}{10}=21$ centimetres.

Thus the answer for the given question is 210 millimeters or 21 centimeters.

Note: We can also change the length of the fish from 40 millimetres to $\dfrac{40}{10}=4$ centimetres. The difference will be similar to $25-4=21$ centimetres. The units can be anything but similar for all of the measurement.