вот по новому функция подсчета
const outputCurrencyCalculation = (e) => {
console.log('e',e)
if(e.target.localName !== 'button'){
setRussianRuble(e.target.value)
}
let inputValue = strToFloat(input)
let outputValue = strToFloat(output)
let inputOutputCoefficient = (inputValue / outputValue)
let calculation = (russianRuble / inputValue ) * inputOutputCoefficient
console.log('inputOutputCoefficient',inputOutputCoefficient)
console.log('(russianRuble / inputValue )',(russianRuble / inputValue ))
console.log('calculation',calculation)
setCalculated(calculation.toFixed(4))
}