For neatness, try to avoid starting sentences with figures. However, if the number at the start of your sentence has a decimal point and you cannot reword the sentence, just leave it as it is.
Starting Sentences with NumbersIt is considered untidy to start sentences with figures. You should either re-word your sentence or write the number in full.
Do Not Expand Numbers with Decimal PlacesIf a number contains a decimal point, just leave it as it is. The "fix" is worse than the "fault." For example:
Capital letters start sentences
Numbers as compound adjectives
How to write numbers in full