mrssnowvp

Learning Support & Inclusive Education

Math Review

on November 15, 2012

We have a test on Monday – parents, here is some information on material that we have covered.

Math Review

 

Place Value:

Millions Hundred Thousands Ten Thousands Thousands Hundreds Tens Ones
8 4 6 7 2 5 1

 

We say: 8 million 4 hundred 67 thousand 2 hundred 51 (8 467 251)

We can write it in expanded form: 8 000 000 + 400 000 + 60 000+ 7 000 + 200 + 50 + 1

Estimating:

Remember: “ If it’s 5 or above, give it a shove; if it’s 4 or below let it go”

So….. 0,1,2,3,4 rounds down

And….5,6,7,8,9 rounds up

For example: 

Round to the nearest 10:

469 would be 470 because we look at the digit in the ones column and then round the digit in the 10s place. The digit in the ones column in this case is 9 so we round up. We round the 6 to a 7 (give it a shove) because it’s in the tens place.

462 would be 460 because we look at the digit in the ones column and then round the digit in the 10s place. The digit in the ones column in this case is 2 so we round down. We round the 6 to a 6 (let it go) because it’s in the tens place.

Round to the nearest 100:

469 would be 500 because we look at the digit in the tens column and then round the digit in the hundreds place. The digit in the tens column in this case is 6 so we round up. We round the 4 to a 5 (give it a shove) because it’s in the hundreds place.

432 would be 400 because we look at the digit in the tens column and then round the digit in the hundreds place. The digit in the tens column in this case is 3 so we round down. We round the 4 to a 4 (let it go) because it’s in the hundreds place.

 

 

Round to the nearest 1000:

2843 would be 3000 because we look at the digit in the hundreds column and then round the digit in the thousands place. The digit in the hundreds column in this case is 8 so we round up. We round the 2 to a 3 (give it a shove) because it’s in the thousands place.

2143 would be 2000 because we look at the digit in the hundreds column and then round the digit in the thousands place. The digit in the hundreds column in this case is 1 so we round down. We round the 2 to a 2 (let it go) because it’s in the thousands place.

 

Mental Math Strategies:

Doubles: 5+5, 12+12 etc

Double plus 1: 5+6= 5+5+1 (so if you know 5+5 you can easily know 5+6)

Doubles plus 2: 5+7= 5+5 +2 (so, if you know 5+5 you can easily know 5+7)

Tens partners: 1+9, 2+8, 3+7, 4+6, 5+5 etc   These can also be used in double digit addition, for example: 24+16 (we know 20+10 is 30 and if we know our tens partners, we know 4+6 is 10 so 30+10 = 40!

The goal is to be able to use these mental math strategies in larger math computation questions to speed the process up.

 

 

 

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