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Numbers & Counting

Counting and Number Names (1 to 100)

When we count, we say numbers in order: 1, 2, 3, 4, 5 … all the way to 100. Each number is one more than the number before it.

Numbers also have names. For example, 7 is seven, 14 is fourteen and 40 is forty. Counting forward means going up (2, 3, 4 …) and counting backward means going down (4, 3, 2 …).

Example 1: What number comes just after 29?
Count one more: 29 → 30. The answer is 30.
Example 2: Count backward: 13, 12, __, 10.
One less than 12 is 11. So the missing number is 11.
Quick recap
  • Counting forward adds 1 each time; counting backward subtracts 1.
  • The number just after a number is 'one more'; just before is 'one less'.
✓ Quick check
Which number comes just before 50?
Just before means one less: 50 − 1 = 49.
Count forward: 67, 68, 69, ___ ?
One more than 69 is 70.

Comparing and Ordering Numbers

To compare two numbers we see which is bigger or smaller. A number with more tens is bigger. If the tens are equal, the one with more ones is bigger.

We can put numbers in order from smallest to largest (ascending) or largest to smallest (descending).

Example 1: Which is greater, 38 or 41?
41 has 4 tens, 38 has 3 tens. So 41 > 38.
Example 2: Arrange smallest to largest: 23, 9, 17.
9, 17, 23.
Quick recap
  • More tens means a bigger number; compare ones only when tens are equal.
  • Ascending = small → big; descending = big → small.
✓ Quick check
Which is the largest number?
91 has 9 tens — the most — so it is largest.
Arrange in ascending order: 45, 54, 15. The first (smallest) is ___.
15 has only 1 ten, so it is the smallest.

Number Patterns & Reasoning

Numbers often follow a pattern — a rule that repeats. Skip counting by 2s (2, 4, 6, 8) or by 5s (5, 10, 15, 20) makes patterns. In olympiads you find the rule, then the next number.

You also reason about positions — like who is 2nd or 5th in a line.

Example 1: Find the next number: 5, 10, 15, 20, __ ?
The rule is +5 each time, so the next is 25.
Example 2: In a line, Riya is 3rd from the front. How many children are in front of her?
Being 3rd means 2 children are ahead of her.
Quick recap
  • Find the rule (e.g. +2, +5, +10), then continue the pattern.
  • Ordinal numbers (1st, 2nd, 3rd …) tell position, not how many.
✓ Quick check
Complete the pattern: 10, 20, 30, ___ ?
The rule is +10, so after 30 comes 40.
Which number does NOT belong: 2, 4, 6, 7, 8?
All are even (skip-counting by 2) except 7, which is odd.
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