Decimals - 4th grade

In this 2nd part of the lesson about adding & subtracting decimals in columns, we first solve a problem with several operations using the correct order of operations. And lastly we have a word problem to solve (by Mathy my mammoth mascot) which involves Mathy and blueberries!

In this 2nd part of the lesson about adding & subtracting decimals in columns, we first solve a problem with several operations using the correct order of operations. And lastly we have a word problem to solve (by Mathy my mammoth mascot) which involves Mathy and blueberries!

Adding and subtracting decimals with column-addition is very easy: just add or subtract like with whole numbers. You just need to line up the two numbers so their decimal points and all other places (ones, tens, tenths, etc.) line up. So, essentially, decimal addition and subtraction exercises are really exercises in lining up the numbers correctly. :) In the 2nd part of this lesson we solve a problem with several operations (with decimals) and one word problem.

Adding and subtracting decimals with column-addition is very easy: just add or subtract like with whole numbers. You just need to line up the two numbers so their decimal points and all other places (ones, tens, tenths, etc.) line up. So, essentially, decimal addition and subtraction exercises are really exercises in lining up the numbers correctly. :) In the 2nd part of this lesson we solve a problem with several operations (with decimals) and one word problem.

In this 2nd part, we learn how to add decimals (with mental math) when one number has 1 decimal digit and the other has 2, such as 0.3 + 0.55. Some children add 3 + 55 = 58, and give the result as 0.58. Instead, we need to think of 0.3 or three tenths as 0.30 (30 hundredths). Then the addition is easy: 0.30 + 0.55 = 0.85.

In this 2nd part, we learn how to add decimals (with mental math) when one number has 1 decimal digit and the other has 2, such as 0.3 + 0.55. Some children add 3 + 55 = 58, and give the result as 0.58. Instead, we need to think of 0.3 or three tenths as 0.30 (30 hundredths). Then the addition is easy: 0.30 + 0.55 = 0.85.

In this first part we add decimals that have two decimal digits, with mental math. This is easy as long as we think in HUNDREDTHS (think of them as fractions). The 2nd part of the lesson deals with additions involving both tenths and hundredths, such as 0.2 + 0.68 (one number has 1 decimal digit; the other has two).

In this first part we add decimals that have two decimal digits, with mental math. This is easy as long as we think in HUNDREDTHS (think of them as fractions). The 2nd part of the lesson deals with additions involving both tenths and hundredths, such as 0.2 + 0.68 (one number has 1 decimal digit; the other has two).

We compare and order decimals that have one or two decimal digits, and also compare them with fractions. This lesson belongs to Math Mammoth Grade 4 curriculum; see for more details.

We compare and order decimals that have one or two decimal digits, and also compare them with fractions. This lesson belongs to Math Mammoth Grade 4 curriculum; see for more details.