Quick Notes

Quick Notes

Mathematics Chapter 2: Basic Operations
2.3 Subtract within 100
2.3  Substract within 100
  Keyword for subtraction operation (-)  
 
  • Find the difference
  • Find the subtraction
  • ...what is left
  • Find the balance
  
 

There are various methods to solve suitable addition operations for numbers up to 100

  • The method count back steps
  • Using common forms
 
Examples of questions and solutions to subtraction operations

Siti has 6 marbles. Siti gave Amir 2 marbles. How many marbles does Siti have left?

Mathematical sentences: \(6 -2= 4\)
Count back steps 

Count back 2 steps from 6:

 6, 5, 4 

The remaining number of marbles that Siti has left is 4.
Using long method

 

We solve this subtraction problem by subtracting the number that is, which we will get.

Then, if there are numbers on the left, continue subtractiong as before.

We write the answer as below.

\(\begin {array}{rr} \space\space6\\-\quad\space\space2\\\hline \space\space4 \\\hline \end {array}\)