Question

''Ignore the zeros after the decimal point' Why??

Answer 1

Its is not completely correct. You cant ignore all zeroes after decimal point.
For eg, zeroes after decimal point in the number 1.002 cant be ignored.

But I think you mean about ignoring the trailing zeroes after the non zero number which comes right to the decimal point.
Its simple because 34.00 is simply equal to 34

But If you ask me, does these zeroes really matter, Then the answer is YES because they are telling you what level of specificity of your measuring tool is. This is called significant figures. For instance if a scale calibrates to the hundredths place, it's not accurate to say simply 2 kgs, you must say 2.00 kgs that way we know that both zeros are not guesses but accurate measurements. Zeroes after a decimal place are always significant.
This indicates precision in a particular number.

You will come to know more about this in your Class 11