a)

$\underset{\text{więcej niz˙ 150}}{\underbrace{169}}+\underset{\text{więcej niz˙ 150}}{\underbrace{188}}>150+150=300$  

$\underset{\text{mniej niz˙ 350}}{\underbrace{345}}+\underset{\text{mniej niz˙ 450}}{\underbrace{418}}<350+450=800$  

$559+359>900$  

$126+269<400$  

$654+349>1000$

 

b)

$\underset{\text{więcej niz˙ 70}}{\underbrace{71}}\cdot 5>70\cdot 5=350$

$\underset{\text{mniej niz˙ 40}}{\underbrace{38}}\cdot 6<40\cdot 6=240$

$91\cdot 9>800$  

$49\cdot 8<400$  

$81\cdot 4>320$

 

c)

$512\cdot 3>1500$  

$1196\cdot 2<2400$  

$251\cdot 5>1250$  

$2109\cdot 4>8400$  

$532\cdot 3<1600$