Place value: The value of a digit based on its position in a number
Note: In grade 1, we focus on ones and tens places.
- Look at each digit in the number
- Identify the position of each digit (rightmost is ones, next is tens)
- State the value of each digit based on its position
The number 24 has two digits: 2 and 4
4 is in the ones place, 2 is in the tens place
2 in tens place = 2 × 10 = 20; 4 in ones place = 4 × 1 = 4
2 tens and 4 ones
• Position matters: Each position represents a different value
• Rightmost digit: Always in the ones place
• Next position: Tens place (10 times the digit)
• Practice Tip: Count by tens and ones to verify place values
- 35 = 3 tens + 5 ones - Practice with different numbers
- 18 = 1 ten + 8 ones - Practice with smaller tens digit
- 42 = 4 tens + 2 ones - Practice with different combinations
- Think of tens as groups of 10, ones as individual units
- Count by tens: 10, 20, 30... to understand the tens place
- Remember: 24 means 2 groups of 10 plus 4 extra ones
Q: How do I know which digit is in the tens place?
A: The tens place is the second digit from the right. In 24, the 2 is in the tens place.
Q: Why is place value important?
A: It helps us understand the actual value of each digit in a number and compare numbers.
Place value ordering: Comparing numbers by examining digits in each place value position
Note: Start comparison from the highest place value (leftmost digit).
- Compare digits in the tens place first
- If tens are the same, compare digits in the ones place
- Determine which number is greater based on the comparison
32 has 3 tens, 28 has 2 tens. Since 3 > 2, 32 > 28
Since tens are different, ones digits don't affect the comparison
32 is greater than 28 because it has more tens
32 is greater than 28 because 32 has 3 tens while 28 has only 2 tens
• Start left: Always compare from the highest place value first
• Tens matter more: A number with more tens is always greater
• Only compare ones if tens are equal: Focus on the highest differing place value
• Practice Tip: Think of tens as groups of 10 objects to visualize the difference
- 45 vs 37 → 45 > 37 (4 tens > 3 tens)
- 51 vs 58 → 58 > 51 (tens equal, 8 ones > 1 one)
- 29 vs 31 → 31 > 29 (3 tens > 2 tens)
- Always start comparing from the leftmost digit
- If tens are the same, compare the ones digits
- More tens always means a greater number
Q: What if both numbers have the same tens digit?
A: Then compare the ones digits. The number with more ones is greater.
Q: Why do we start comparing from the left?
A: Because the leftmost digits have the greatest place value and determine the overall size.
Rounding: Finding the closest multiple of 10 to a given number
Note: Numbers ending in 1-4 round down, numbers ending in 5-9 round up.
- Identify the ones digit in the number
- Apply the rounding rule: 1-4 round down, 5-9 round up
- Determine the nearest ten
In 23, the ones digit is 3
Since 3 is less than 5, we round down
23 rounds down to 20
20
• Rounding rule: 1-4 round down, 5-9 round up
• Focus on ones: The ones digit determines whether to round up or down
• Nearest ten: The result is always a multiple of 10
• Practice Tip: Use a number line to visualize which ten is closer
- 17 rounds to 20 (ones digit 7 ≥ 5, round up)
- 42 rounds to 40 (ones digit 2 ≤ 4, round down)
- 35 rounds to 40 (ones digit 5 ≥ 5, round up)
- Remember the rhyme: "Four or less, let it rest; Five or more, raise the score"
- Look at the ones digit only to decide rounding direction
- Use a number line to see which ten is closer
Q: What happens when the ones digit is exactly 5?
A: When the ones digit is 5, we round up to the next ten.
Q: Why do we round numbers?
A: Rounding helps make numbers easier to work with and gives approximate values.
Number comparison: Using place value to determine which number is larger or smaller
Note: When tens are equal, compare the ones digits.
- Compare digits in the tens place
- If tens are equal, compare digits in the ones place
- Determine which number is greater based on the comparison
Both numbers have 4 tens, so we need to compare ones
47 has 7 ones, 43 has 3 ones. Since 7 > 3, 47 > 43
47 is greater than 43 because they have equal tens but 47 has more ones
47 is greater than 43 because they have the same tens (4), but 47 has more ones (7) than 43 (3)
• Equal tens: When tens are the same, compare the ones digits
• Ones matter: If tens are equal, the number with more ones is greater
• Systematic approach: Always compare from highest place value down
• Practice Tip: Count the extra ones to see the difference visually
- 52 vs 58 → 58 > 52 (equal tens, 8 ones > 2 ones)
- 31 vs 36 → 36 > 31 (equal tens, 6 ones > 1 one)
- 74 vs 74 → 74 = 74 (equal tens and equal ones)
- When tens are equal, only the ones digits matter
- Count the extra ones to see how much greater one number is
- Remember: same tens means we only need to look at ones
Q: What if both numbers have the same tens and ones?
A: Then the numbers are equal. For example, 35 = 35.
Q: Do I always need to break down the numbers?
A: Not always, but breaking down helps understand why one number is greater.
Ascending order: Arranging numbers from smallest to largest
Note: Use place value to compare numbers systematically.
- Compare tens digits first to group numbers
- Within each group, compare ones digits
- Arrange from smallest to largest
Numbers with 2 tens: 25, 28; Numbers with 3 tens: 34, 37
For 2 tens: 25 < 28 (5 ones < 8 ones); For 3 tens: 34 < 37 (4 ones < 7 ones)
25, 28, 34, 37 (from smallest tens to largest, then smallest ones to largest)
25, 28, 34, 37
• Group by tens: Numbers with fewer tens come first
• Within groups: Compare ones digits when tens are equal
• Systematic approach: Organize numbers by tens, then by ones
• Practice Tip: Use place value breakdown to make comparisons clearer
- 41, 38, 46, 32 → 32, 38, 41, 46 (group by tens first)
- 53, 57, 49, 51 → 49, 51, 53, 57 (4 tens first, then 5 tens)
- 26, 31, 24, 35 → 24, 26, 31, 35 (order by tens, then by ones)
- Start by grouping numbers with the same tens digit
- Within each group, order by ones digits
- Remember: numbers with fewer tens always come before numbers with more tens
Q: What if I have many numbers to order?
A: Group them by tens first, then order within each group by ones digits.
Q: Can I order them randomly?
A: No, use place value systematically to ensure correct order.