Wykonujemy obliczenia:

$145-94=145-90-4=55-4=51$  

lub 

$145-94=145-45-49=100-49=51$

 

$154-82=154-80-2=74-2=72$

lub

$154-82=154-54-28=100-28=72$

 

$129-55=129-50-5=79-5=74$

lub

$129-55=129-29-26=100-26=74$

 

$149-97=149-90-7=59-7=52$

lub

$149-97=149-49-48=100-48=52$

 

$115-21=115-20-1=95-1=94$

lub

$115-21=115-15-6=100-6=94$

 

$168-76=168-70-6=98-6=92$

lub

$168-76=168-68-8=100-8=92$

 

$137-73=137-70-3=67-3=64$

lub

$137-73=137-37-36=100-36=64$

 

$178-81=178-80-1=98-1=97$

lub

$178-81=178-78-3=100-3=97$

 

$143-81=143-80-1=63-1=62$

lub

$143-81=143-43-38=100-38=62$  

 

Uzupełniamy tabelę:

139 - 41 = 98	145 - 94 = 51	154 - 82 = 72	129 - 55 = 74	149 -97 = 52
115 - 21 = 94	168 - 76 = 92	137 - 73 = 64	178 - 81 = 97	143 - 81 = 62