A. Let countingDown = function(startNumber) {
If ( startNumber >0) {
console.log(startNumber) ;
return countingDown(startNUmber);
} else {
return startNumber;
}};

B. Const factorial =numVar => {
If (numVar < 0) return;
If ( numVar === 0 ) return 1;
return numVar * factorial ( numVar - 1 );
};

C. Function factorial ( numVar ) {
If (numVar < 0) return;
If ( numVar === 0 ) return 1;
return numVar -1;

D. Const sumToTen = numVar => {
If (numVar < 0)
Return;
return sumToTen(numVar + 1)};