Post on 27-Jun-2015
description
transcript
Addition , Subtraction , Multiplication
Addittion
The sum is always greater than the numbers being added,Except when one of the numbers being added is 0(zero).
example
3 1 4
When you change the order of numbers while adding,the sum doesn’t change.
14+13=27
13+14=27
• The sum of zero and any number is the same number .
• 21+0=21• 0+33=33
• When you add 1 to a number the answer is the number after.
• 8+1=9• 1+25=26
Adding bigger numbers
• Adding bigger numbers is a lot like adding 3-digit numbers.start with the ones Then move on to the hundreds and so on.
• There were 2392 peoples on the first day of the book fair and 5106 people on the second day. How many people on both the days?
• 2392+5106=?
• Step 1:add the onesTHOUSANDS HUNDREDS TENS ONES
2 3 9 2
5 1 0 6
8
Step 2:add the tens
THOUSANDS HUNDREDS TENS ONES
2 3 9 25 1 0 6
9 8
Step 3:add the hundredsThousands Hundred Tens Ones
2 3 9 2
5 1 0 6
4 9 8
Step 4:add the thousandsThousands Hundreds Tens Ones
2 3 9 2
5 1 0 6
7 4 9 8
Word Problems
• Anagha collects match box covers.She has 96 of them.her friend,Shakti has 19 more than Anagha.How many match box does Shakti have? +1
• 96+19=? 96• +19• 11 5
• There were 728 girls in the girls section.There were 900 boys in the boys section.How many childrens are there in all?
• 900+728=? 900• + 728• 16 2 8
Subtraction
The answer in subtraction is called difference.
Examples
2 1 1
Remember
When we subtract a number from itself , the answer is always 0.
When we subtract zero from a number , the answer is itself.
14-14=012-0=12
Using subtraction
• To find out what was taken away• We use subtraction when we know the
original number and what is left over but need to find out what was taken away.
• Eighteen children were on the swing.Some children went home.there are now five children on the swing.How many children went home?18-?=5
• We can find the answer by subtraction.• 18-5=13 so, 18 – 13 = 5• Ans-13 children went home.
To find out how many more needed
• We use subtraction when we have to find out how many more to be added to get the given number.
• Varuns mother needs 15 apples to make fruit salad.She has 9 apples.How many more does she need? 9+?=15.
• This can be solved using subtraction• 15-9=? 15-9 = 6 so,9+6=15• Ans – Varuns mother needs 6 more apples for the
fruit salad.
Subtracting 3-digit numbers
• Regrouping tens to ones.• Sometimes when you subtract,you may
not have enough ones.You may have to regroup 1 to tens.
• 573 peoples came for exibition in the morning.256 people left in afternoon.How many are still at the exibition? 573-256=?
Step 1.subtract the ones
Hundreds Tens Ones
5 6 7 12 3
2 5 6
6
Step2.subtract the tens
Hundreds Tens Ones
5 6 7 12 3
2 5 6
1 6
Step3.subtract the hundredsHundreds Tens Ones
5 6 7 12 3
2 5 6
3 1 6
Word problems
• Janes book has 77 pages.Last night she read 22 pages.How many more pages to read?
• 7 7• - 2 2• 5 5
Multiplication
When each group has the same number , we use multiplication to find out how many are there in all.
•
2
2 2 6
3groups of 2 each is 6.
3 * 2 = 6
Remember • Any number multiplied by 1 is that number itself• Any number multiplied by 0 is always 0.• The order of numbers being multiplied does not
matter.
Multiplying 3-digit numbers
• Lorries carry motorbikes over long distances.If each lorry can carry 132 motorbikes.How many bikes will 3 such lorries carry ? 132*3=
Step 1.multiply the ones
Hundreds Tens Ones
1 3 2
3
6
Step 2.multiply the tensHundreds tens Ones
1 3 2
3
9 6
Step 3.multiply the hundredshundreds tens Ones
1 3 2
3
3 9 6
Ans – 369 motorbikes would be carried by 3 lorries.
Word problems• 23 buses , each carrying 13 school children were
taken to the book fair.How many children went to the book fair ? 23*13 = 299 2 3
• 1 3• 6 9• 2 3 0• 2 9 9
Revision • 480+309• 723+168• 184+272• 639+384• 376+921• 246+389
Add these sums
Subtract and multiply
• 983-126 132*96• 728*45 895-56• 859-666 300-142• 900-700• 800*69• 231*2
• Done by Kumari Urvashi• 5 C