title: Initializer 'init(_:)' requires that 'Decimal' conform to 'BinaryInteger'
body: <p>I'm trying to make a compound interest calculator app and I'm getting this error when I return the formula of compound interest -> Initializer 'init(_:)' requires that 'Decimal' conform to 'BinaryInteger' </p>
  
  <p>The error appear when I implement the compound interest formula:
  return balance * pow((1 + rate / 100), Int(mounths))</p>
  
  <pre><code>struct CompoundView: View {
  @State var accountBalance: Decimal?
  @State var percentagePerMounth: Decimal?
  @State var numberOfMounths: Decimal?
  
  @State var totalCompoundInterest = " "
  
  var total: Decimal {
      guard let balance = self.accountBalance, let rate = self.percentagePerMounth, let mounths = self.numberOfMounths else {
          return 0
      }
      return balance * pow((1 + rate / 100), Int(mounths))
  }
  
  // Currency Formater
  static var currencyFormatter: NumberFormatter {
      let nf = NumberFormatter()
      nf.numberStyle = .currency
      nf.isLenient = true
      return nf
  }
  
  // Percent Formatter
  static var percentFormatter: NumberFormatter {
      let nf = NumberFormatter()
      nf.numberStyle = .percent
      // preserve input as-is, otherwise 10 becomes 0.1, which makes
      // sense but is less intuitive for input
      nf.multiplier = 1
      nf.isLenient = true
      return nf
  }
  
  // Months Formatter
  static var monthsFormatter: NumberFormatter {
      let nf = NumberFormatter()
      nf.numberStyle = .decimal
      nf.isLenient = true
      return nf
  }
  
  // Compound Interest View
  var body: some View {
  
      VStack {
          HStack {
              Text("Start Balance")
                  .font(.subheadline)
                  .padding(.vertical)
              Spacer()
              DecimalField("$0.00", value: $accountBalance, formatter: Self.currencyFormatter)
                  .keyboardType(.decimalPad)
                  .font(.largeTitle)
                  .multilineTextAlignment(.trailing)
          }
          .foregroundColor(.white)
          Divider().background(Color.white)
  
          HStack {
              Text("Percentage per month")
                  .font(.subheadline)
                  .padding(.vertical)
              Spacer()
              DecimalField("0%", value: $percentagePerMounth, formatter: Self.percentFormatter)
                  .keyboardType(.decimalPad)
                  .font(.largeTitle)
                  .multilineTextAlignment(.trailing)
          }
          .foregroundColor(.white)
          Divider().background(Color.white)
  
          HStack {
              Text("Number of months")
                  .font(.subheadline)
                  .padding(.vertical)
              Spacer()
              DecimalField("0", value: $numberOfMounths, formatter: Self.monthsFormatter)
                  .keyboardType(.decimalPad)
                  .font(.largeTitle)
                  .multilineTextAlignment(.trailing)
          }
          .foregroundColor(.white)
          Divider().background(Color.white)
  
          // Calculate Button
          Button(action: {
              hideKeyboard()
              self.totalCompoundInterest = Self.currencyFormatter.string(for: self.total)!
  
          }) {
              Text("Calculate")
                  .font(.body)
                  .foregroundColor(Color.white)
          }
  
          Text(self.totalCompoundInterest)
              .foregroundColor(.white)
              .font(.largeTitle)
              .padding()
  
          Spacer()
      }
  } 
  </code></pre>
  
  <p>}</p>