Mastering Multi-Digit Addition

What is the sum of $$234,567$$ and $$345,678$$ ?

Estimate the sum of $$89,456$$ and $$12,345$$ by rounding each number to the nearest ten thousand.

A school library has $$123,456$$ books. They received a donation of $$34,567$$ books. How many books does the library have now?

What is the sum of $$456,789$$ and $$543,211$$ ?

Estimate the sum of $$234,567$$ and $$765,432$$ by rounding each number to the nearest hundred thousand.

A factory produced $$345,678$$ toys in January and $$456,789$$ toys in February. How many toys did the factory produce in total?

What is the sum of $$678,901$$ and $$321,099$$ ?

Estimate the sum of $$123,456$$ and $$876,543$$ by rounding each number to the nearest hundred thousand.

A company sold $$567,890$$ units of product A and $$432,110$$ units of product B. How many units did the company sell in total?

What is the sum of $$789,012$$ and $$210,988$$ ?