Question

1. add these numbers using the breaking down method:

a) $125 + 423$ b) $522 + 274$
c) $987 + 112$ d) $209 + 460$
e) $475 + 324$ f) $213 + 236$

1. add these numbers using the adding on method:

a) $420 + 136$ b) $145 + 233$
c) $809 + 170$ d) $736 + 162$
e) $654 + 205$ f) $542 + 337$

1. add by using the easiest method for you:

a) $21 + 49$ b) $160 + 840$
c) $901 + 999$ d) $58 + 142$
e) $430 + 670$ f) $290 + 410$

Explanation:

1. Add these numbers using the breaking down method:

Step1: Split into place values

Break each number into hundreds, tens, ones.

Step2: Add each place value

Sum hundreds, tens, ones separately.

Step3: Combine the sums

Add the results of each place value.

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a) $125 + 423$

Step1: Split into place values

$125 = 100 + 20 + 5$; $423 = 400 + 20 + 3$

Step2: Add each place value

$100+400=500$; $20+20=40$; $5+3=8$

Step3: Combine the sums

$500 + 40 + 8 = 548$

b) $522 + 274$

Step1: Split into place values

$522 = 500 + 20 + 2$; $274 = 200 + 70 + 4$

Step2: Add each place value

$500+200=700$; $20+70=90$; $2+4=6$

Step3: Combine the sums

$700 + 90 + 6 = 796$

c) $987 + 112$

Step1: Split into place values

$987 = 900 + 80 + 7$; $112 = 100 + 10 + 2$

Step2: Add each place value

$900+100=1000$; $80+10=90$; $7+2=9$

Step3: Combine the sums

$1000 + 90 + 9 = 1099$

d) $209 + 460$

Step1: Split into place values

$209 = 200 + 0 + 9$; $460 = 400 + 60 + 0$

Step2: Add each place value

$200+400=600$; $0+60=60$; $9+0=9$

Step3: Combine the sums

$600 + 60 + 9 = 669$

e) $475 + 324$

Step1: Split into place values

$475 = 400 + 70 + 5$; $324 = 300 + 20 + 4$

Step2: Add each place value

$400+300=700$; $70+20=90$; $5+4=9$

Step3: Combine the sums

$700 + 90 + 9 = 799$

f) $213 + 236$

Step1: Split into place values

$213 = 200 + 10 + 3$; $236 = 200 + 30 + 6$

Step2: Add each place value

$200+200=400$; $10+30=40$; $3+6=9$

Step3: Combine the sums

$400 + 40 + 9 = 449$

Step1: Start with the larger number

Use the first number as the base.

Step2: Add the second number in parts

Add hundreds, then tens, then ones to the base.

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a) $420 + 136$

Step1: Start with base number

Base: $420$

Step2: Add hundreds, then tens, then ones

$420 + 100 = 520$; $520 + 30 = 550$; $550 + 6 = 556$

b) $145 + 233$

Step1: Start with base number

Base: $233$ (larger number)

Step2: Add hundreds, then tens, then ones

$233 + 100 = 333$; $333 + 40 = 373$; $373 + 5 = 378$

c) $809 + 170$

Step1: Start with base number

Base: $809$

Step2: Add hundreds, then tens

$809 + 100 = 909$; $909 + 70 = 979$

d) $736 + 162$

Step1: Start with base number

Base: $736$

Step2: Add hundreds, then tens, then ones

$736 + 100 = 836$; $836 + 60 = 896$; $896 + 2 = 898$

e) $654 + 205$

Step1: Start with base number

Base: $654$

Step2: Add hundreds, then ones

$654 + 200 = 854$; $854 + 5 = 859$

f) $542 + 337$

Step1: Start with base number

Base: $542$

Step2: Add hundreds, then tens, then ones

$542 + 300 = 842$; $842 + 30 = 872$; $872 + 7 = 879$

Step1: Use compatible pairs (when applicable)

Pair numbers that sum to 10, 100, or 1000 for quick addition.

Step2: Add directly if simpler

For straightforward sums, add the numbers directly.

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a) $21 + 49$

Step1: Add directly (or use pairs)

$21 + 49 = 70$

b) $160 + 840$

Step1: Use compatible pairs

$160 + 840 = (100+800) + (60+40) = 900 + 100 = 1000$

c) $901 + 999$

Step1: Adjust to compatible pairs

$901 + 999 = (900+1) + 999 = 900 + (1+999) = 900 + 1000 = 1900$

d) $58 + 142$

Step1: Use compatible pairs

$58 + 142 = (50+140) + (8+2) = 190 + 10 = 200$

e) $430 + 670$

Step1: Use compatible pairs

$430 + 670 = (400+600) + (30+70) = 1000 + 100 = 1100$

f) $290 + 410$

Step1: Use compatible pairs

$290 + 410 = (200+400) + (90+10) = 600 + 100 = 700$

Answer:

a) $548$
b) $796$
c) $1099$
d) $669$
e) $799$
f) $449$

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2. Add these numbers using the adding on method: