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 37 has two digits: 3 and 7
7 is in the ones place, 3 is in the tens place
3 in tens place = 3 × 10 = 30; 7 in ones place = 7 × 1 = 7
3 tens and 7 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
- 45 = 4 tens + 5 ones - Practice with different numbers
- 28 = 2 tens + 8 ones - Practice with smaller tens digit
- 61 = 6 tens + 1 one - 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: 37 means 3 groups of 10 plus 7 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 37, the 3 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
42 has 4 tens, 38 has 3 tens. Since 4 > 3, 42 > 38
Since tens are different, ones digits don't affect the comparison
42 is greater than 38 because it has more tens
42 is greater than 38 because 42 has 4 tens while 38 has only 3 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
- 54 vs 47 → 54 > 47 (5 tens > 4 tens)
- 61 vs 68 → 68 > 61 (tens equal, 8 ones > 1 one)
- 39 vs 42 → 42 > 39 (4 tens > 3 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.
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 5 tens, so we need to compare ones
56 has 6 ones, 51 has 1 one. Since 6 > 1, 56 > 51
56 is greater than 51 because they have equal tens but 56 has more ones
56 is greater than 51 because they have the same tens (5), but 56 has more ones (6) than 51 (1)
• 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
- 43 vs 48 → 48 > 43 (equal tens, 8 ones > 3 ones)
- 67 vs 62 → 67 > 62 (equal tens, 7 ones > 2 ones)
- 55 vs 55 → 55 = 55 (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, 45 = 45.
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 3 tens: 35, 38; Numbers with 4 tens: 43, 47
For 3 tens: 35 < 38 (5 ones < 8 ones); For 4 tens: 43 < 47 (3 ones < 7 ones)
35, 38, 43, 47 (from smallest tens to largest, then smallest ones to largest)
35, 38, 43, 47
• 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
- 51, 48, 56, 42 → 42, 48, 51, 56 (group by tens first)
- 63, 67, 59, 61 → 59, 61, 63, 67 (5 tens first, then 6 tens)
- 36, 41, 34, 45 → 34, 36, 41, 45 (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.
Descending order: Arranging numbers from largest to smallest
Note: Use place value to compare numbers systematically, starting with largest.
- Compare tens digits first to group numbers
- Within each group, compare ones digits from largest to smallest
- Arrange from largest to smallest
Numbers with 5 tens: 56, 52; Numbers with 4 tens: 49, 43
For 5 tens: 56 > 52 (6 ones > 2 ones); For 4 tens: 49 > 43 (9 ones > 3 ones)
56, 52, 49, 43 (from largest tens to smallest, then largest ones to smallest)
56, 52, 49, 43
• Start with largest: Numbers with more tens come first
• Within groups: Compare ones digits when tens are equal
• Reverse order: Arrange from largest to smallest
• Practice Tip: Think of descending as going "down" from large to small
- 61, 58, 66, 53 → 66, 61, 58, 53 (group by tens first)
- 47, 52, 44, 55 → 55, 52, 47, 44 (5 tens first, then 4 tens)
- 39, 33, 41, 37 → 41, 39, 37, 33 (order by tens, then by ones)
- Start with the highest tens digit and work down
- Within each tens group, order by ones digits from highest to lowest
- Remember: numbers with more tens always come before numbers with fewer tens
Q: How is descending order different from ascending?
A: Descending goes from largest to smallest, ascending goes from smallest to largest.
Q: Do I use the same comparison method?
A: Yes, use the same place value comparison, just arrange in reverse order.