Excel stores numbers between -1.798 x10+308 and 1.798 x 10+308 for a numeric range of ±10+308. A scientific calculator handles a range of 10±99. Although the largest number that Excel can store is 1.798 x 10+308, the largest number that you can type is 9.999 x 10+307. If you type in a larger number, Excel will treat it as a character string.
Most scientific calculations have reasonable results somewhere in the range of 10-40 to 10+40. When these numbers are used in an equation, the intermediate results are often quite large. If the intermediate results exceed the range of the computer then an overflow condition will return an error.