Lab6_ECYT | Python Fiddle

def main():
    loops=0
    maxentry=2

print('Select Conversion Type:')
    print('1 - Miles to kilometer')
    print('2 - Gallons to liters')
    print('3 - Pounds to kilograms')
    print('4 - Inches to centimeters')
    print('5 - Fahrenheit to Celsius')
    choice = float(input('Choose what value to convert:'))

if (choice==1):return miles
    else:
        print('Invalid selection')

miles=float(input('How many miles to convert? '))
    while miles<0 and loops<maxentry:
        loops+=1
        print('The value you have entered is invalid. You have', 3-loops, 'attempts left. Please try again: ')
        miles=float(input('How many miles to convert? '))
    if loops==maxentry and miles<0:
        print('ERROR! Invalid entry after', maxentry+1, 'attempts.')
    else:
        milesToKm(miles)
        loops=0

#Farenheit
        F=float(input('How many degrees to convert? '))
        while F>1000 and loops<maxentry:
            loops+=1
            print('The value you have entered is invalid. You have', 3-loops, 'attempts left. Please try again: ')
            F=float(input('How many degrees to convert? '))
        if loops==maxentry and F >= 1000:
            print('ERROR! Invalid entry after', maxentry+1, 'attempts.')
        else:
            FahToCel(F)
            loops=0

#gallons
            gallon=float(input('How many gallons to convert? '))
            while gallon<0 and loops<maxentry:
                loops+=1
                print('The value you have entered is invalid. You have', 3-loops, 'attempts left. Please try again: ')
                gallon=float(input('How many gallons to convert? '))
            if loops==maxentry and gallon < 0:
                print('ERROR! Invalid entry after', maxentry+1, 'attempts.')
            else:
                GalToLit(gallon)
                loops=0
                
                #pounds
                pound=float(input('How many pounds to convert? '))
                while pound<0 and loops<maxentry:
                    loops+=1
                    print('The value you have entered is invalid. You have', 3-loops, 'attempts left. Please try again: ')
                    pound=float(input('How many pounds to convert? '))
                if loops==maxentry and pound < 0:
                    print('ERROR! Invalid entry after', maxentry+1, 'attempts.')
                else:
                    PoundsToKg(pound)
                    loops=0
        
                    #inches
                    inch=float(input('How many inches to convert? '))
                    while inch<0 and loops<maxentry:
                        loops+=1
                        print('The value you have entered is invalid. You have', 3-loops, 'attempts left. Please try again: ')
                        inch=float(input('How many inches to convert? '))
                    if loops==maxentry and inch < 0:
                        print('ERROR! Invalid entry after', maxentry+1, 'attempts.')
                    else:
                        InchesToCm(inch)
                        loops=0

def milesToKm(miles):
    loops=0
    kilo=miles*1.6
    print('That is',format(kilo), 'kilometers.')

def FahToCel(F):
    loops=0
    C=(F-32)*(5/9)
    print('That is',format(C), 'Celsius.')

def GalToLit(gallon):
    loops=0
    liter=gallon*3.9
    print('That is',format(liter), 'liters.')

def PoundsToKg(pound):
    loops=0
    kgram=pound*.45
    print('That is',format(kgram), 'kilograms.')

def InchesToCm(inch):
    loops=0
    cmeter=inch*2.54
    print('That is',format(cmeter), 'centimeters.')

main()

Python Fiddle

Python Cloud IDE