\[\boxed{\mathbf{1}\mathbf{.70}}\]
Пояснение.
Решение.
\[\textbf{а)}\ 98 + 49 =\]
\[= (98 + 2) + (49 - 2) =\]
\[= 100 + 47 = 147\]
\[\textbf{б)}\ 497 + 445 =\]
\[= (497 + 3) + (445 - 3) =\]
\[= 500 + 442 = 942\]
\[\textbf{в)}\ 338 + 46 =\]
\[= (338 + 2) + (46 - 2) =\]
\[= 340 + 44 = 384\]