The letter e is used in many mathematical calculations to stand for a particular number known as the exponential constant. The exponential constant is an important mathematical constant and is given the symbol e. Its value is approximately 2.718.

The negative sign on an exponent means the reciprocal. Think of it this way: just as a positive exponent means repeated multiplication by the base, a negative exponent means repeated division by the base.

The equation for an exponential curve is y = aebx, where a and b are arbitrary constants and e is the mathematical constant e. In your curve, the constants have been adjusted so that a = 3E+07 ≡ 3.0 x 107 ≡ 30,000,000 and b = 1.8299.

The Excel TREND function is used to calculate a linear trend line through a given set of dependent y-values and, optionally, a set of independent x-values and return values along the trend line.

Here are the steps to follow:

1. Put the X values for which you want predictions in a column of cells, such as B8:B10.
2. Select the cells in which you want the predictions displayed; in this example C8:C10.
3. Enter the following formula: =TREND(C3:C8,B3:B8,B10:B12)
4. Press Ctrl+Shift+Enter to complete the formula.

The Excel TREND function calculates the linear trend line through a given set of y-values and (optionally), a given set of x-values. The function then extends the linear trendline to calculate additional y-values for a further supplied set of new x-values. An array known y-values. One or more arrays of known x-values.

To calculate the trend percentage for 2018, you have to divide $40,000 by $30,000 to get 1.33, and then multiply it by 100. The result, which is 133%, is your trend percentage for 2018. If the trend percentage is greater than 100%, it means the balance in that year has increased over the base period.