The Decimals We Know

Comparing and ordering decimals
We do not compare them by how many digits they have, but the numbers before the decimal point.
Conversion of fractions to decimals, and vice versa
We usually change the denominator to 10,100 and so on to facilitate the conversion. If the denominator is 10, than the number has a decimal place.
Addition and subtraction up to 2 decimals (without using the calculator)
We just have to ignore the decimal point while adding or subtracting and add the decimal point afterwards.
Multiplication and division of decimals up to 2 decimals places by a 1-digit whole number(without using the calculator)
We also ignore the decimal point while dividing or multiplication but we have to count how many numbers behind the decimal in BOTH numbers and add the decimal point in front of the number of the numbers.
Multiplication and division of decimals up to 3 decimals places by tens, hundreds and thousands (without using the calculator)
If we have to multiply or divide a number by tens, hundreds and thousands, we just have to move the decimal point. If we are dividing, we need to move the decimal point to the left. It is vice versa for multiplication. If we are diving by tens, we move by one digit.
Division of a whole number by a whole number with answer in decimal form
We just divide them without the decimal point and just add back later.
Approximation and estimation
We approximate usually by the tenths. We normally use approximation and estimation in our daily life when we are dealing with money, etc when we need to pay money for our groceries and want change, we need to estimate to the nearest whole number which is bigger than the cost.
Use of calculators
We use calculators when we need to do our maths and the adults need it to sometimes to calculate the bills, etc.
Done by Sher Li, Zhi Qi and Guang Jun

1 comment:

  1. Dear Team

    Thanks for giving a quick and good summary on the topic :D

    With these set of skills, how could we apply them in our daily activities?
    You mentioned about using approximation and estimation when we deal with money - when do we need exact figures, why we use approximation/estimation?