--- a/.emacs-my	Mon Feb 22 11:32:37 2021 +0200
+++ b/.emacs-my	Wed Apr 07 22:48:39 2021 +0300
@@ -1652,10 +1652,13 @@
         (insert result)))))
 
 (defun my-calc-line (arg)
-  "Evaluate expression in current line and display the result in
-the echo area by skipping final '=' sign. With prefix ARG
-non-nil, insert the result at the end of line and space if
-necessary for delimiting."
+  "Evaluate calc expression in current line and display the
+result in the echo area by skipping everything after the final
+'=' sign.
+
+With prefix ARG non-nil or repeating command interactively,
+insert the result at the end of line + add a space if necessary
+for delimiting clearing everything after '=' sign if it is here."
   (interactive "P")
   (require 'calc)
   (save-excursion
@@ -1667,9 +1670,13 @@
       (setq end (point))
       (setq expr (buffer-substring-no-properties beg end))
       (setq result (calc-eval expr))
-      (if (null arg)
+      (if (and (null arg) (not (eq 'my-calc-line last-command)))
           (message "%s = %s" expr result)
         (end-of-line)
+        (setq end (point))
+        (when (search-backward "=" beg t)
+          (forward-char 1)
+          (delete-region (point) end))
         (unless (eq (char-before) ?\ )
           (insert ?\ ))
         (insert result)))))