well, one story is 4m 2dm and 17 cm.
now, there are 100 centimeters in 1 meter, so in 4 meters there are 400 cm then.
now, there are 10 decimeters in 1 meter, therefore, 10 centimeters in 1 dm, so in 2 dm is then 20 cm.
in 17 centimeters, is just 17 cm :).
so, the 1 story of the building is 400 + 20 + 17 centimeters, or 437 cm.
now, the building has 17 stories, so 17 * 437 or 7429 cm.
which will then be 7400 cm or 74 meters.
and
20 cm or 2 dm.
and
9 cm.
so, 74 meters, 2 decimeters and 9 centimeters.