1, 2, 3, 6, 9, 18, 27, 54. When you make different pair combinations of these factors, it would give you the factor pairs of 54….As you notice, all these factor pairs would result in the number 54 when multiplied together.

• x 54 = 54.
• x 27 = 54.
• x 18 = 54.

Here’s the trick: Any time you square a two-digit number that ends in 5, the last digits of the answer will be 25 and the digits before that are given by multiplying the first digit of the number by the number that’s one greater.

To add two numbers mentally, add the digits separately. Add the tens digits and then look at the ones digits to decide what the answer ends in. For example in 32 + 29, we add the tens digits first. 3 + 2 = 5.

How to add and subtract in your head

1. To add 9 to another number, add 10 and then subtract 1: 36 + 9 = 36 + 10 – 1 = 45.
2. To add 18 to another number, add 20 and then subtract 2: 48 + 18 = 48 + 20 – 2 = 66.
3. To add 97 to another number, add 100 and then subtract 3: 439 + 97 = 439 + 100 – 3 = 536.

Addition Tips and Tricks

1. Count From A Number Upwards. Example: 6 + 3.
2. Jump Strategy. We can also count by 2s or 10s, or make any “jumps” we want to help us solve a calculation.
3. Adding Up To Ten.
4. Do The Tens Last.
5. Aim for Ten.
6. Compensation Method.
7. Double when the numbers are the same.
8. Double if the numbers are close, then fix.

How to add minutes and seconds:

1. Add the minutes together.
2. Add the seconds together.
3. If the number of seconds is 60 or more, regroup the seconds into minutes: Subtract 60 from the seconds. Add 1 to the minutes. Repeat until the seconds are less than 60.

Mental math is a group of skills that allow people to do math “in their head” without using pencil and paper or a calculator. Mental math is useful in school and in everyday life. Mental math can help kids understand math concepts better and get to the answer faster.

This is a complete lesson with instruction and exercises for the student about adding two 2-digit numbers mentally, meant for 2nd grade. The basic idea is to add in parts, such as tens and ones separately, or add in parts in some other way. Example 1. Add in parts 40 + 55.

7 reasons why doing mental maths is important: It stimulates children’s interest in maths. Improves the self-confidence of the child. Helps with the application skills in maths. Strongly associated with better memory skills.

So let’s get on to the practical part of this writing: mental math strategies for EVERYONE.

• The “9-trick”. To add 9 to any number, first add 10, and then subtract 1.
• Doubles + 1.
• Use addition facts when adding bigger numbers.
• Subtract by adding.
• Five times a number.
• Four and eight times a number.
• Multiply in parts.

Mental math refers to fact learning, mental computation, and computational estimation. The Atlantic Canada Mathematics Curriculum supports the acquisition of these skills through the development of thinking strategies across grade levels.

The Atlantic Canada Mathematics Curriculum supports the acquisition of these skills through the development of thinking strategies across grade levels. Mental math refers to fact learning, mental computation, and computational estimation.

Three digit numbers are from 100 to 999. We know that there are nine one-digit numbers, i.e., 1, 2, 3, 4, 5, 6, 7, 8 and 9.