Grade 2 | MATHEMATICS
WEEK 18 • STUDENT TEXTBOOK • DAYS 86–90
Read each lesson with a parent or teacher and study the worked example. Then answer the questions for that day in the Week 18 Practice Workbook.
Week 18 Student Textbook | Week 18 Practice Workbook | Week 18 Teacher Guide | Week 17 Student Textbook | Week 19 Student Textbook | Grade 2 index
Day 86: Hundreds, Tens and Ones in New Ways
A three-digit number has hundreds, tens and ones. In 245, the 2 means 2 hundreds, the 4 means 4 tens and the 5 means 5 ones.
100 is the same as 10 tens. So 245 can also be shown as 24 tens and 5 ones. When you see 10 or more tens, trade 10 tens for 1 hundred to find the number.
Worked example: What number is 3 hundreds, 5 tens and 2 ones?
- 3 hundreds is 300 and 5 tens is 50.
- 300 + 50 + 2 = 352.
Worked answer: 352.
Day 87: Count Within 1000 and Skip-Count
You can count forward from any number up to 1000. When you count by 5s, the ones digit goes 0, 5, 0, 5. When you count by 10s, the tens digit grows by 1 each time. When you count by 100s, the hundreds digit grows by 1.
Watch what happens near a new hundred. Counting by 5s: 390, 395, 400, 405. Counting by 10s: 680, 690, 700, 710. The hundreds digit changes when you reach the next hundred.
Worked example: Count by 5s: 45, 50, 55, what comes next?
- Counting by 5s adds 5 each time.
- 55 + 5 = 60.
Worked answer: 60.
Day 88: Read, Write and Compare Numbers
A number can be written three ways. As a numeral: 462. As a number name: four hundred sixty-two. In expanded form: 400 + 60 + 2.
To compare two three-digit numbers, look at the hundreds first. If the hundreds are the same, compare the tens, then the ones. Use > for greater than, < for less than and = for equal. The open side of the sign faces the greater number.
Worked example: Write 735 in expanded form.
- 7 hundreds is 700 and 3 tens is 30.
- Add the 5 ones.
Worked answer: 700 + 30 + 5.
Day 89: Hands-On: Number-Card Game
To find 10 more or 10 less in your head, change the tens digit by 1. To find 100 more or 100 less, change the hundreds digit by 1. Watch for numbers like 395: 10 more is 405, because 10 tens make a new hundred.
In today’s game you will make three-digit numbers with digit cards, then compare them and find 10 or 100 more and less.
Worked example: What is 10 less than 300?
- 300 has 30 tens. Take away 1 ten: 29 tens.
- 29 tens is 290.
Worked answer: 290.
Day 90: Independent Check: Place Value
Today you will answer on your own.
Use what you learned this week: hundreds, tens and ones, counting, writing numbers, comparing, and 10 or 100 more or less.
Worked example: How many hundreds are in 600?
- 600 is 6 groups of 100.
- So there are 6 hundreds.
Worked answer: 6.
Week 18 Student Textbook | Week 18 Practice Workbook | Week 18 Teacher Guide | Week 17 Student Textbook | Week 19 Student Textbook | Grade 2 index