Another test under the debugger to give you food for thought:

  DB<13> printf "%d", 35784.45 * 100;
3578444
  DB<14> printf "%s", 35784.45 * 100
3578445
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But the real question was addressed earlier by davido: where is the 35784.45 piece of data coming from? If it is read in a text file or from a text-format network, then using regexes or printf "%s", ... is not only right, but is probably the best solution. If it comes from a previous calculation or from binary data, then it may be slightly more complicated, details would be needed about its original format.