Math - Chapter 2 Place Value in Addition

Lesson 2.1 More than Two Addends

Try some for your self:

Lesson 2.2 & 2.3 Using Place Value to Regroup

Use base-ten master to create your own manipulative for you to use in solving math problems using place value to regroup.

In addition you add the ones first;

If there are more then 9 ones, you need to regroup the ones.

12 ones regroups as 1 ten + 2 ones ( 10 + 2) 

Then add the tens

62 = 6 tens + 2 ones or 60 + 2

Try some one your own

In addition you add the ones first;

If there are more then 9 ones, you need to regroup the ones.

13 ones regroups as = 1 ten + 3 ones ( 10 + 3)

Then add the tens

If there are more then 9 tens, you need to regroup the tens.

13 tens regroups a 1 = hundred + 3 tens (100 + 30)

Then you can add your hundreds.

133 = 1 hundred + 3 tens + 3 ones 

                                                                      = 100 + 30 + 3

Lesson 4 - Estimating Sums and Differences

You are finding an estimate when you round numbers to find about how many you have.

Rounding to the nearest ten means to find the ten a number is the closest to in value.

Round 23 to the nearest ten;

If the number in the ones column is 4 or less, you round down to the lower/nearest ten which would be 20.

Round 15 to the nearest ten;

If the number in the ones column is 5 or more, you round up to the higher/nearest ten which would be 20.

So 15, 16, 17, 18, 19,  would round up to 20, 20 stays/rounds  20

and 21, 22, 23, 24 would round down to 20. 

Make a number line of your own and try rounding these numbers to the nearest ten;

34    rounds to ______        12 rounds to ______,  28 rounds to _____

Rounding to the nearest hundred means to find the hundred a number is the closest to in value.

Round 187 to the nearest hundred

If the number in the tens place is 5 or more, you need to round up to the nearest hundred.  So 187 would round to 200.

Round 249 to the nearest hundred

If the number in the tens place is 4 or less, your need to round down to the nearest hundred.  So 249 would round to 200.

So all the numbers for 150, 151, 152, ... to 199 would round to 200, and 200 rounds to/ stays 200.  All to numbers 249, 248, 247, 246, ... would round down to 200.

Make a number line of your own and try rounding these numbers to the nearest hundred;

104 rounds to _____,  281 rounds to ______,  151 rounds to _____

Visit these Internet sites to explore further and develop your skills at rounding numbers

Lesson 5 - Choosing Addition or Subtraction 

When you read a story problem, you can decide if your should add or subtract if you look for 'key words."

When solving story problems use these steps:

Try writing your own story problems and don't forget to use key words.

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